:root {
  color-scheme: light;
  --ink: #111415;
  --muted: #6e7471;
  --line: #dfe4e0;
  --paper: #fffcf8;
  --surface: #f4f1eb;
  --surface-strong: #e7ece7;
  --coral: #9e6047;
  --coral-dark: #783f30;
  --coral-soft: #f5ebe6;
  --green: #1f7264;
  --green-soft: #e7f1ee;
  --blue: #355d77;
  --blue-soft: #e7eff4;
  --amber: #956d31;
  --amber-soft: #f3eadb;
  --violet: #665d7f;
  --violet-soft: #eeecf4;
  --danger: #b33b37;
  --gold: #b48845;
  --void: #090b0d;
  --bone: #f7f2ea;
  --crystal: #67aab5;
  --shadow: 0 18px 42px rgb(23 28 30 / 10%);
  --radius-s: 8px;
  --radius-m: 12px;
  --radius-l: 24px;
  --ease: 180ms cubic-bezier(.2,.8,.2,1);
}

* {
  box-sizing: border-box;
  letter-spacing: 0;
}

::selection {
  color: #fff;
  background: color-mix(in srgb, var(--coral) 78%, #000);
}

html,
body {
  width: 100%;
  min-height: 100%;
  margin: 0;
}

body {
  color: var(--ink);
  background:
    radial-gradient(circle at 10% 8%, rgb(225 233 229 / 70%) 0 18%, transparent 34%),
    linear-gradient(118deg, rgb(9 11 13 / 5%) 0 1px, transparent 1px 100%),
    linear-gradient(135deg, #efefea 0%, #f7f2ea 52%, #eef1f2 100%);
  background-size: auto, 34px 34px, auto;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-size: 14px;
}

button,
input,
select,
video {
  color: inherit;
  font: inherit;
  letter-spacing: 0;
}

button {
  cursor: pointer;
}

button,
input {
  transition:
    background-color var(--ease),
    border-color var(--ease),
    color var(--ease),
    box-shadow var(--ease),
    transform var(--ease),
    opacity var(--ease);
}

button:focus-visible,
input:focus-visible,
select:focus-visible {
  outline: 2px solid #216fc4;
  outline-offset: 2px;
}

.preview-shell {
  display: grid;
  grid-template-columns: 410px minmax(360px, 780px);
  align-items: start;
  justify-content: center;
  gap: 24px;
  min-height: 100vh;
  padding: 20px;
}

.device {
  position: sticky;
  top: 24px;
  width: 390px;
  max-width: 100%;
  height: min(844px, calc(100vh - 40px));
  min-height: 760px;
  padding: 12px;
  border-radius: 34px;
  background:
    linear-gradient(180deg, #1b1e20 0%, #0f1214 100%);
  box-shadow:
    0 26px 66px rgb(24 30 34 / 28%),
    inset 0 1px 0 rgb(255 255 255 / 8%);
}

.device::before {
  position: absolute;
  inset: 10px;
  border: 1px solid rgb(255 255 255 / 3%);
  border-radius: 28px;
  pointer-events: none;
  content: "";
}

.device-screen {
  position: relative;
  display: grid;
  grid-template-rows: 34px 50px minmax(0, 1fr) 68px;
  height: 100%;
  overflow: hidden;
  border-radius: 26px;
  background:
    linear-gradient(180deg, rgb(255 252 248 / 45%) 0%, rgb(244 241 235 / 0%) 32%),
    var(--surface);
}

.device-screen.immersive {
  grid-template-rows: 34px 52px minmax(0, 1fr) 0;
}

.system-bar {
  display: grid;
  grid-template-columns: 1fr 104px 1fr;
  align-items: center;
  padding: 0 18px;
  color: #66706d;
  background: var(--bone);
  font-size: 12px;
  font-weight: 650;
}

.system-island {
  width: 104px;
  height: 8px;
  border-radius: 4px;
  background: #25282b;
}

.system-icons {
  text-align: right;
  font-size: 10px;
  word-spacing: 4px;
}

.mini-header {
  display: grid;
  grid-template-columns: 42px minmax(0, 1fr) 42px;
  align-items: center;
  padding: 0 12px;
  border-bottom: 1px solid transparent;
  background: color-mix(in srgb, var(--bone) 92%, #fff);
}

.mini-header.with-line {
  border-bottom-color: var(--line);
}

.header-title {
  overflow: hidden;
  text-align: center;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 15px;
  font-weight: 760;
  letter-spacing: 0.01em;
}

.header-icon {
  display: grid;
  width: 36px;
  height: 36px;
  padding: 0;
  place-items: center;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: #5c625d;
  font-size: 24px;
}

.header-icon:hover {
  background: var(--surface);
  color: var(--ink);
}

.header-icon[aria-hidden="true"] {
  pointer-events: none;
  visibility: hidden;
}

.mobile-app {
  min-height: 0;
  overflow-x: hidden;
  overflow-y: auto;
  overscroll-behavior: contain;
  background: var(--surface);
}

.mobile-app::-webkit-scrollbar {
  width: 0;
}

.page {
  min-height: 100%;
  padding: 14px 18px 22px;
}

.page-heading {
  display: flex;
  align-items: flex-end;
  justify-content: space-between;
  gap: 12px;
  margin: 22px 0 12px;
}

.page-heading h2,
.page-heading p {
  margin: 0;
}

.page-heading h2 {
  font-size: 20px;
  font-weight: 800;
}

.page-heading p {
  color: var(--muted);
  font-size: 11px;
}

.section-label {
  margin: 22px 0 12px;
  font-size: 18px;
  font-weight: 800;
}

.section-label:first-child {
  margin-top: 0;
}

.eyebrow {
  margin: 0 0 7px;
  color: var(--coral);
  font-size: 11px;
  font-weight: 760;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.primary-command,
.secondary-command,
.text-command {
  min-height: 40px;
  border-radius: var(--radius-s);
  font-weight: 740;
}

.primary-command {
  padding: 0 16px;
  border: 1px solid color-mix(in srgb, var(--coral) 84%, #000);
  color: #fff;
  background: linear-gradient(180deg, color-mix(in srgb, var(--coral) 90%, #fff), var(--coral-dark));
  box-shadow: 0 10px 24px rgb(159 58 53 / 20%);
}

.primary-command:hover {
  border-color: var(--coral-dark);
  background: var(--coral-dark);
}

.secondary-command {
  padding: 0 14px;
  border: 1px solid var(--line);
  background: var(--paper);
}

.secondary-command:hover,
.route-switcher button:hover:not(.active),
.shield-test:hover {
  border-color: color-mix(in srgb, currentColor 24%, var(--line));
  box-shadow: 0 8px 18px rgb(23 28 30 / 7%);
  transform: translateY(-1px);
}

.text-command {
  padding: 0 6px;
  border: 0;
  color: var(--coral);
  background: transparent;
}

.subjects-page {
  padding-top: 16px;
  background:
    linear-gradient(180deg, rgb(255 255 255 / 70%) 0%, rgb(245 247 246 / 0%) 38%),
    var(--surface);
}

.home-topline {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin: 0 0 16px;
}

.brand-lockup {
  display: flex;
  align-items: center;
  gap: 12px;
  min-width: 0;
}

.brand-symbol {
  display: grid;
  flex: 0 0 auto;
  width: 42px;
  height: 42px;
  place-items: center;
  border-radius: 8px;
  color: #f8f4ec;
  background:
    linear-gradient(145deg, #101314, #2c3030);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 14%),
    0 12px 24px rgb(23 26 28 / 16%);
  font-family: "Songti SC", "STSong", serif;
  font-size: 19px;
  font-weight: 500;
}

.brand-copy {
  min-width: 0;
}

.brand-copy strong,
.brand-copy span {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.brand-copy strong {
  font-size: 18px;
  font-weight: 500;
  letter-spacing: 0;
}

.brand-copy span {
  margin-top: 4px;
  color: var(--muted);
  font-size: 11px;
}

.streak {
  display: grid;
  width: 42px;
  height: 42px;
  padding: 0;
  place-items: center;
  border: 1px solid #d8c2a1;
  border-radius: 50%;
  color: var(--amber);
  background: rgb(255 254 252 / 82%);
  box-shadow: 0 10px 20px rgb(33 40 42 / 8%);
}

.streak span,
.streak small {
  display: block;
  line-height: 1;
}

.streak span {
  font-size: 16px;
  font-weight: 500;
}

.streak small {
  color: #8a8d89;
  font-size: 9px;
}

.home-hero {
  position: relative;
  min-height: 218px;
  margin: 0 -18px;
  padding: 22px 18px 18px;
  overflow: hidden;
  color: #f8f4ec;
  background:
    linear-gradient(145deg, rgb(9 11 13 / 99%) 0%, rgb(29 34 35 / 98%) 54%, rgb(73 58 41 / 96%) 100%);
  border-bottom: 1px solid rgb(255 255 255 / 4%);
}

.home-hero::after {
  position: absolute;
  right: -42px;
  bottom: -68px;
  width: 164px;
  height: 164px;
  border: 1px solid rgb(248 244 236 / 12%);
  border-radius: 50%;
  content: "";
}

.home-hero::before {
  position: absolute;
  inset: 0;
  background:
    linear-gradient(108deg, transparent 0 43%, rgb(255 255 255 / 4%) 43% 44%, transparent 44% 100%),
    repeating-linear-gradient(0deg, transparent 0 14px, rgb(247 242 234 / 10%) 15px, transparent 16px 28px),
    radial-gradient(circle at 22% 24%, rgb(180 136 69 / 20%) 0 2px, transparent 3px);
  pointer-events: none;
  content: "";
}

.hero-copy {
  position: relative;
  z-index: 2;
  max-width: 240px;
}

.hero-copy span,
.hero-copy p {
  color: rgb(248 244 236 / 70%);
}

.hero-copy span {
  font-size: 11px;
  letter-spacing: 0.14em;
}

.hero-copy h1 {
  margin: 12px 0 9px;
  font-family: "Songti SC", "STSong", serif;
  font-size: 30px;
  font-weight: 500;
  line-height: 1.22;
}

.hero-copy p {
  margin: 0;
  overflow-wrap: anywhere;
  font-size: 12px;
  line-height: 1.55;
}

.hero-mark {
  position: absolute;
  right: 18px;
  bottom: 60px;
  display: grid;
  width: 112px;
  height: 88px;
  align-content: center;
  opacity: 0.72;
}

.hero-mark span {
  position: absolute;
  z-index: 1;
  top: -22px;
  left: 8px;
  color: rgb(247 242 234 / 38%);
  font-family: Georgia, "Times New Roman", serif;
  font-size: 86px;
}

.hero-mark i {
  display: block;
  height: 1px;
  margin: 6px 0;
  background: linear-gradient(90deg, transparent, rgb(180 136 69 / 46%), rgb(103 170 181 / 24%), transparent);
}

.hero-action {
  position: absolute;
  z-index: 2;
  right: 18px;
  bottom: 18px;
  left: 18px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  min-height: 46px;
  padding: 0 14px 0 16px;
  border: 1px solid rgb(248 244 236 / 22%);
  border-radius: 10px;
  color: #151719;
  background: linear-gradient(180deg, #fffaf1, #f1e7d6);
  box-shadow: 0 16px 34px rgb(0 0 0 / 18%);
  font-weight: 500;
  text-align: left;
}

.hero-action:hover {
  transform: translateY(-2px);
  box-shadow: 0 19px 38px rgb(0 0 0 / 22%);
}

.hero-action b {
  font-size: 22px;
  font-weight: 400;
}

.knowledge-daily-hero {
  min-height: 184px;
  margin: 0;
  border-top: 1px solid rgb(255 255 255 / 4%);
}

.knowledge-daily-hero .hero-mark {
  bottom: 46px;
}

.course-ad-carousel {
  position: relative;
  min-height: 218px;
  margin: 0 -18px;
  overflow: hidden;
  color: var(--bone);
  background:
    linear-gradient(145deg, rgb(9 11 13 / 99%) 0%, rgb(31 36 37 / 98%) 58%, rgb(89 62 39 / 96%) 100%);
  border-bottom: 1px solid rgb(255 255 255 / 4%);
}

.course-ad-carousel::before {
  position: absolute;
  inset: 0;
  z-index: 1;
  background:
    radial-gradient(circle at 74% 24%, rgb(180 136 69 / 28%) 0 2px, transparent 3px),
    radial-gradient(circle at 84% 64%, rgb(103 170 181 / 18%) 0 1px, transparent 2px),
    repeating-linear-gradient(0deg, transparent 0 15px, rgb(247 242 234 / 8%) 16px, transparent 17px 30px);
  pointer-events: none;
  content: "";
}

.course-ad-carousel::after {
  position: absolute;
  z-index: 1;
  right: -48px;
  bottom: -70px;
  width: 168px;
  height: 168px;
  border: 1px solid rgb(247 242 234 / 12%);
  border-radius: 50%;
  pointer-events: none;
  content: "";
}

.course-ad-track {
  position: relative;
  z-index: 2;
  display: flex;
  width: 300%;
  min-height: 218px;
  animation: course-ad-slide 12s infinite;
}

.course-ad-carousel:hover .course-ad-track {
  animation-play-state: paused;
}

.course-ad-slide {
  position: relative;
  display: grid;
  flex: 0 0 33.3333%;
  min-width: 0;
  min-height: 218px;
  align-content: start;
  padding: 24px 18px 18px;
}

.course-ad-copy {
  max-width: 246px;
}

.course-ad-copy span,
.course-ad-copy p {
  color: rgb(247 242 234 / 72%);
}

.course-ad-copy span {
  font-size: 11px;
  letter-spacing: 0.14em;
}

.course-ad-copy h1 {
  margin: 12px 0 9px;
  font-family: "Songti SC", "STSong", serif;
  font-size: 29px;
  font-weight: 500;
  line-height: 1.22;
  text-wrap: balance;
}

.course-ad-copy p {
  margin: 0;
  font-size: 12px;
  line-height: 1.58;
}

.course-ad-action {
  position: absolute;
  right: 18px;
  bottom: 18px;
  left: 18px;
  display: grid;
  grid-template-columns: minmax(0, 1fr) auto;
  align-items: center;
  min-height: 46px;
  padding: 0 16px;
  border: 1px solid rgb(247 242 234 / 22%);
  border-radius: 10px;
  color: #151719;
  background: linear-gradient(180deg, #fffaf1, #f1e7d6);
  box-shadow: 0 16px 34px rgb(0 0 0 / 18%);
  font-weight: 500;
  text-align: left;
}

.course-ad-action::after {
  color: rgb(21 23 25 / 70%);
  font-size: 20px;
  font-weight: 400;
  content: "›";
}

.course-ad-action:hover {
  transform: translateY(-2px);
  box-shadow: 0 19px 38px rgb(0 0 0 / 22%);
}

.course-ad-dots {
  position: absolute;
  z-index: 3;
  right: 18px;
  top: 20px;
  display: flex;
  gap: 6px;
}

.course-ad-dots span {
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: rgb(247 242 234 / 35%);
  animation: course-ad-dot 12s infinite;
}

.course-ad-dots span:nth-child(2) {
  animation-delay: 4s;
}

.course-ad-dots span:nth-child(3) {
  animation-delay: 8s;
}

@keyframes course-ad-slide {
  0%, 27% { transform: translateX(0); }
  33%, 60% { transform: translateX(-33.3333%); }
  66%, 93% { transform: translateX(-66.6666%); }
  100% { transform: translateX(0); }
}

@keyframes course-ad-dot {
  0%, 27% { background: var(--gold); transform: scale(1.28); }
  33%, 100% { background: rgb(247 242 234 / 35%); transform: scale(1); }
}

.home-status {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 1px;
  margin: 16px 0;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: var(--line);
  box-shadow: 0 12px 26px rgb(24 30 34 / 5%);
}

.home-status div {
  display: grid;
  gap: 4px;
  min-width: 0;
  padding: 13px 8px;
  background: rgb(255 252 248 / 94%);
  text-align: center;
}

.home-status strong {
  font-size: 18px;
  font-weight: 500;
  color: color-mix(in srgb, var(--ink) 90%, var(--gold));
}

.home-status span {
  color: var(--muted);
  font-size: 10px;
}

.progress-gate-page {
  position: relative;
  display: grid;
  min-height: 100%;
  overflow: hidden;
  place-items: center;
  padding: 28px 20px 30px;
  background:
    linear-gradient(180deg, rgb(247 242 234 / 94%) 0%, rgb(232 238 235 / 86%) 100%);
}

.progress-gate-orbit {
  position: absolute;
  inset: 58px 38px auto;
  height: 240px;
  border: 1px solid rgb(180 136 69 / 16%);
  border-radius: 50%;
  transform: rotate(-12deg);
}

.progress-gate-orbit::before,
.progress-gate-orbit::after {
  position: absolute;
  inset: 24px;
  border: 1px solid rgb(103 170 181 / 13%);
  border-radius: inherit;
  content: "";
}

.progress-gate-orbit::after {
  inset: 52px;
  border-color: rgb(31 114 100 / 12%);
}

.progress-gate-panel {
  position: relative;
  z-index: 1;
  display: grid;
  width: 100%;
  gap: 16px;
}

.progress-gate-kicker {
  margin: 0;
  color: var(--green);
  font-size: 11px;
  font-weight: 800;
  letter-spacing: 0.14em;
}

.progress-gate-panel h1 {
  max-width: 270px;
  margin: -8px 0 0;
  font-size: 30px;
  font-weight: 850;
  line-height: 1.12;
}

.progress-gate-copy {
  max-width: 286px;
  margin: -4px 0 4px;
  color: #555f5a;
  font-size: 13px;
  line-height: 1.72;
}

.battery-card {
  position: relative;
  display: grid;
  gap: 14px;
  padding: 18px;
  border: 1px solid rgb(17 20 21 / 8%);
  border-radius: var(--radius-s);
  background:
    linear-gradient(180deg, rgb(255 252 248 / 96%), rgb(246 249 247 / 92%));
  box-shadow: 0 18px 40px rgb(23 28 30 / 10%);
}

.battery-head,
.battery-meta {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.battery-head span {
  color: var(--muted);
  font-size: 12px;
  font-weight: 700;
}

.battery-head strong {
  color: var(--ink);
  font-size: 34px;
  font-weight: 850;
  line-height: 1;
}

.battery-shell {
  position: relative;
  height: 48px;
  margin-right: 10px;
  padding: 6px;
  border: 2px solid #1d2422;
  border-radius: 9px;
  background: rgb(255 255 255 / 62%);
  box-shadow:
    inset 0 0 0 1px rgb(255 255 255 / 64%),
    0 9px 18px rgb(17 20 21 / 8%);
}

.battery-shell::after {
  position: absolute;
  top: 14px;
  right: -9px;
  width: 5px;
  height: 18px;
  border-radius: 0 4px 4px 0;
  background: #1d2422;
  content: "";
}

.battery-level {
  position: absolute;
  inset: 6px auto 6px 6px;
  max-width: calc(100% - 12px);
  border-radius: 5px;
  background: linear-gradient(90deg, var(--green), var(--crystal), var(--gold));
  box-shadow: 0 0 18px rgb(103 170 181 / 26%);
  animation: battery-rise 900ms cubic-bezier(.2,.8,.2,1) both;
}

.battery-cells {
  position: relative;
  z-index: 1;
  display: grid;
  height: 100%;
  grid-template-columns: repeat(10, minmax(0, 1fr));
  gap: 4px;
}

.battery-cells span {
  border-radius: 3px;
  background: rgb(17 20 21 / 7%);
  box-shadow: inset 0 0 0 1px rgb(255 255 255 / 24%);
}

.battery-cells span.active {
  background: rgb(255 252 248 / 36%);
}

.battery-meta {
  min-width: 0;
  color: var(--muted);
  font-size: 11px;
}

.battery-meta span:first-child {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.progress-gate-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 8px;
}

.progress-gate-stats div {
  display: grid;
  gap: 5px;
  min-width: 0;
  padding: 12px 7px;
  border: 1px solid rgb(17 20 21 / 7%);
  border-radius: var(--radius-s);
  background: rgb(255 252 248 / 72%);
  text-align: center;
}

.progress-gate-stats strong {
  overflow: hidden;
  text-overflow: ellipsis;
  color: color-mix(in srgb, var(--ink) 86%, var(--gold));
  font-size: 18px;
  font-weight: 820;
  white-space: nowrap;
}

.progress-gate-stats span {
  color: var(--muted);
  font-size: 10px;
}

.progress-gate-button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 48px;
  margin-top: 4px;
  padding: 0 18px;
  border: 1px solid color-mix(in srgb, var(--ink) 88%, var(--gold));
  border-radius: var(--radius-s);
  color: #fff;
  background: linear-gradient(180deg, #202522, #0d1010);
  box-shadow: 0 18px 36px rgb(17 20 21 / 20%);
  font-weight: 800;
}

.progress-gate-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 22px 42px rgb(17 20 21 / 24%);
}

.progress-gate-button span {
  color: var(--gold);
  font-size: 24px;
  line-height: 1;
}

.progress-gate-note {
  justify-self: center;
  color: #727974;
  font-size: 11px;
}

@keyframes battery-rise {
  from { width: 0; opacity: 0.45; }
}

.continue-band {
  margin-top: 16px;
  padding: 15px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: rgb(255 254 254 / 92%);
  box-shadow: 0 12px 26px rgb(24 30 34 / 5%);
}

.continue-top,
.continue-meta,
.course-heading,
.knowledge-topline,
.quiz-progress-head,
.result-head,
.video-meta,
.lesson-row,
.profile-stat-line {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
}

.continue-top span {
  color: var(--green);
  font-size: 12px;
  font-weight: 500;
}

.continue-top small,
.continue-meta,
.video-meta {
  color: var(--muted);
  font-size: 11px;
}

.continue-band h2 {
  margin: 10px 0 6px;
  font-size: 19px;
  line-height: 1.35;
}

.progress-track {
  height: 5px;
  margin: 12px 0 12px;
  overflow: hidden;
  border-radius: 3px;
  background: var(--surface-strong);
}

.progress-track span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--green), var(--crystal), var(--gold));
  transition: width 420ms var(--ease);
}

.path-list {
  display: grid;
  gap: 1px;
  margin: 0 -2px -2px;
  overflow: hidden;
  border-radius: var(--radius-s);
  background: var(--line);
}

.path-row {
  display: grid;
  grid-template-columns: 36px minmax(0, 1fr) auto;
  align-items: center;
  gap: 10px;
  width: 100%;
  min-height: 58px;
  padding: 8px 10px;
  border: 0;
  background: var(--paper);
  text-align: left;
}

.path-row:hover {
  background: #fff;
}

.path-row.active {
  background:
    linear-gradient(90deg, rgb(31 117 102 / 9%), rgb(255 254 254 / 96%) 58%);
}

.path-index {
  color: #a5aaac;
  font-family: Georgia, "Times New Roman", serif;
  font-size: 13px;
}

.path-row strong,
.path-row small {
  display: block;
  min-width: 0;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.path-row strong {
  font-size: 13px;
  font-weight: 500;
}

.path-row small {
  margin-top: 4px;
  color: var(--muted);
  font-size: 10px;
}

.path-row b {
  color: #9ca3a6;
  font-size: 18px;
  font-weight: 400;
}

.subject-path-list {
  margin: 0 0 4px;
}

.subject-path-row.is-coming {
  color: var(--muted);
}

.subject-path-row.is-coming strong,
.subject-path-row.is-coming small {
  opacity: 0.66;
}

.subject-grid,
.subject-carousel {
  display: grid;
}

.subject-carousel {
  --subject-card-width: 25%;
  --subject-gap: 12.5%;
  grid-auto-columns: var(--subject-card-width);
  grid-auto-flow: column;
  gap: var(--subject-gap);
  margin: 0 -18px;
  padding: 0 18px 12px;
  overflow-x: auto;
  overflow-y: hidden;
  scroll-padding: 18px;
  scroll-snap-type: x mandatory;
  overscroll-behavior-x: contain;
  -webkit-overflow-scrolling: touch;
}

.subject-carousel::-webkit-scrollbar {
  height: 0;
}

.subject-card {
  position: relative;
  min-width: 0;
  min-height: 94px;
  padding: 10px 8px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: rgb(255 254 254 / 92%);
  box-shadow: 0 10px 22px rgb(24 30 34 / 5%);
  scroll-snap-align: start;
  text-align: left;
}

.subject-card:hover:not(:disabled) {
  border-color: color-mix(in srgb, currentColor 46%, var(--line));
  transform: translateY(-2px);
  box-shadow: 0 14px 30px rgb(24 30 34 / 9%);
}

.subject-card.is-coming {
  background:
    linear-gradient(180deg, rgb(255 254 254 / 90%), rgb(245 247 246 / 80%));
}

.subject-card.is-coming::after {
  position: absolute;
  right: 8px;
  bottom: 8px;
  width: 5px;
  height: 5px;
  border-radius: 50%;
  background: currentColor;
  opacity: 0.32;
  content: "";
}

.subject-card:disabled {
  cursor: default;
  opacity: 0.68;
}

.subject-card.coral { color: var(--coral); }
.subject-card.blue { color: var(--blue); }
.subject-card.green { color: var(--green); }
.subject-card.amber { color: var(--amber); }
.subject-card.violet { color: var(--violet); }

.subject-icon,
.knowledge-icon {
  display: grid;
  place-items: center;
  border-radius: 7px;
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 800;
}

.subject-icon {
  width: 26px;
  height: 26px;
  margin-bottom: 8px;
  border: 1px solid color-mix(in srgb, currentColor 30%, transparent);
  background: color-mix(in srgb, currentColor 9%, #fff);
  font-size: 15px;
}

.subject-card strong,
.subject-card span,
.subject-card small {
  display: block;
  max-width: 100%;
  overflow-wrap: anywhere;
}

.subject-card strong {
  color: var(--ink);
  font-size: 12px;
  font-weight: 500;
  line-height: 1.25;
}

.subject-card span {
  margin-top: 4px;
  font-size: 9px;
  color: #687376;
  opacity: 1;
  line-height: 1.35;
}

.subject-card small {
  margin-top: 6px;
  color: #858b8e;
  font-size: 9px;
}

.subject-list {
  display: grid;
  gap: 1px;
  margin-top: 12px;
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: var(--line);
}

.subject-list-row {
  display: grid;
  grid-template-columns: 32px minmax(0, 1fr) auto auto;
  align-items: center;
  gap: 10px;
  min-height: 54px;
  padding: 9px 12px;
  border: 0;
  background: rgb(255 254 254 / 92%);
  text-align: left;
}

.subject-list-row:hover {
  background: #fff;
}

.subject-list-row:hover strong {
  color: var(--coral);
}

.subject-list-row span {
  display: grid;
  width: 30px;
  height: 30px;
  place-items: center;
  border-radius: 7px;
  background: color-mix(in srgb, currentColor 10%, #fff);
  font-family: Georgia, "Times New Roman", serif;
  font-weight: 500;
}

.subject-list-row strong {
  min-width: 0;
  overflow: hidden;
  color: var(--ink);
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 13px;
  font-weight: 500;
}

.subject-list-row small {
  color: var(--muted);
  font-size: 10px;
}

.subject-list-row b {
  color: #a0a6a8;
  font-size: 17px;
  font-weight: 400;
}

.subject-list-row.coral { color: var(--coral); }
.subject-list-row.blue { color: var(--blue); }
.subject-list-row.green { color: var(--green); }
.subject-list-row.amber { color: var(--amber); }
.subject-list-row.violet { color: var(--violet); }

.motto-band,
.daily-strip,
.subject-arrow {
  display: none;
}

.course-heading {
  align-items: flex-start;
  margin-bottom: 18px;
}

.knowledge-page {
  padding: 0 0 24px;
  background:
    linear-gradient(180deg, #fbf8f2 0%, #f4efe7 100%);
}

.knowledge-topbar {
  display: grid;
  grid-template-columns: 32px 32px minmax(0, 1fr) auto;
  align-items: center;
  gap: 8px;
  margin: 0 -18px;
  padding: 12px 14px 8px;
}

.knowledge-bar-icon {
  width: 28px;
  height: 28px;
  padding: 0;
  border: 0;
  border-radius: 50%;
  background: transparent;
  color: #232321;
  font-size: 18px;
}

.knowledge-bar-icon:hover {
  background: rgb(0 0 0 / 4%);
}

.knowledge-wordmark {
  display: grid;
  justify-items: center;
  text-align: center;
}

.knowledge-wordmark strong {
  font-size: 15px;
  font-weight: 800;
  letter-spacing: 0.1em;
}

.knowledge-wordmark span {
  margin-top: 1px;
  color: #5f615c;
  font-size: 10px;
  letter-spacing: 0.14em;
}

.knowledge-pill {
  display: inline-grid;
  place-items: center;
  min-width: 62px;
  height: 30px;
  padding: 0 10px;
  border-radius: 999px;
  color: #93918e;
  background: #ece8e0;
  font-size: 12px;
  font-weight: 700;
}

.knowledge-cover {
  margin: 0 -18px;
  padding: 4px 18px 16px;
  text-align: center;
}

.knowledge-cover p {
  margin: 10px 0 6px;
  color: #42443f;
  font-size: 14px;
  font-weight: 700;
  letter-spacing: 0.08em;
}

.knowledge-cover h1 {
  margin: 0;
  font-size: 31px;
  line-height: 1.06;
  font-weight: 800;
  text-wrap: balance;
}

.knowledge-cover span {
  display: inline-block;
  margin-top: 8px;
  color: #6a6762;
  font-size: 11px;
}

.knowledge-visual {
  margin: 2px -18px 0;
  padding: 0 18px;
}

.knowledge-visual-panel {
  position: relative;
  min-height: 204px;
  overflow: hidden;
  border-radius: 0;
  background:
    linear-gradient(180deg, rgb(255 255 255 / 3%) 0%, transparent 28%),
    var(--void);
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 5%);
}

.knowledge-visual-panel::before {
  position: absolute;
  inset: 0;
  background:
    repeating-linear-gradient(0deg, transparent 0 18px, rgb(247 242 234 / 8%) 19px, transparent 20px 36px),
    linear-gradient(90deg, transparent, rgb(180 136 69 / 12%), transparent);
  pointer-events: none;
  content: "";
}

.knowledge-shelf {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 9px;
  padding: 18px 10px 16px;
}

.knowledge-shelf-empty {
  grid-column: 1 / -1;
  padding: 40px 0;
  color: rgb(255 255 255 / 70%);
  text-align: center;
  font-size: 12px;
}

.knowledge-shelf-tile {
  min-height: 118px;
  padding: 8px 6px;
  border: 0;
  border-radius: 4px;
  background: linear-gradient(180deg, #93908b 0%, #6f6c67 100%);
  color: #fff;
  text-align: center;
  box-shadow:
    inset 0 0 0 1px rgb(255 255 255 / 10%),
    0 12px 20px rgb(0 0 0 / 16%);
}

.knowledge-shelf-tile:hover {
  transform: translateY(-2px);
  box-shadow:
    inset 0 0 0 1px rgb(255 255 255 / 14%),
    0 15px 24px rgb(0 0 0 / 20%);
}

.knowledge-shelf-tile span {
  display: block;
  margin-bottom: 6px;
  font-size: 10px;
  opacity: 0.88;
}

.knowledge-shelf-tile b {
  display: grid;
  place-items: center;
  min-height: 44px;
  font-size: 24px;
}

.knowledge-shelf-tile small {
  display: block;
  margin-top: 6px;
  font-size: 9px;
  line-height: 1.4;
}

.tone-coral {
  background: linear-gradient(180deg, #9b948d 0%, #776f67 100%);
}

.tone-blue {
  background: linear-gradient(180deg, #849295 0%, #687477 100%);
}

.tone-green {
  background: linear-gradient(180deg, #87938d 0%, #68756e 100%);
}

.tone-amber {
  background: linear-gradient(180deg, #94928e 0%, #76736e 100%);
}

.tone-violet {
  background: linear-gradient(180deg, #989592 0%, #7a7672 100%);
}

.knowledge-section {
  padding: 16px 0 0;
}

.knowledge-section-head {
  display: grid;
  gap: 10px;
  justify-items: center;
}

.knowledge-section-head strong {
  font-size: 15px;
  font-weight: 700;
  letter-spacing: 0.06em;
}

.knowledge-steps {
  display: flex;
  gap: 8px;
  flex-wrap: wrap;
  justify-content: center;
}

.knowledge-step {
  min-width: 22px;
  height: 24px;
  padding: 0 4px;
  border: 0;
  border-radius: 999px;
  background: transparent;
  color: #5f5d59;
  font-size: 12px;
}

.knowledge-step:hover {
  color: var(--ink);
  background: rgb(0 0 0 / 5%);
}

.knowledge-feature-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin: 13px 0 0;
}

.knowledge-feature-card {
  display: grid;
  min-width: 0;
  padding: 0;
  border: 0;
  background: transparent;
  cursor: pointer;
  text-align: center;
}

.knowledge-feature-thumb {
  display: grid;
  place-items: center;
  height: 112px;
  overflow: hidden;
  background:
    linear-gradient(180deg, #9b9893 0%, #7e7b76 100%);
  box-shadow: inset 0 0 0 1px rgb(255 255 255 / 10%);
}

.knowledge-feature-card:hover .knowledge-feature-thumb {
  box-shadow:
    inset 0 0 0 1px rgb(255 255 255 / 14%),
    0 14px 24px rgb(0 0 0 / 10%);
}

.knowledge-feature-thumb span {
  color: #f5f4ef;
  font-family: Georgia, serif;
  font-size: 29px;
}

.knowledge-feature-card strong {
  display: block;
  margin-top: 8px;
  color: var(--ink);
  font-size: 12px;
  font-weight: 700;
}

.knowledge-feature-card span {
  display: block;
  margin-top: 4px;
  color: #6a6763;
  font-size: 10px;
}

.knowledge-feature-card small {
  display: block;
  margin-top: 5px;
  color: #6c675d;
  font-size: 10px;
}

.knowledge-point-section {
  padding: 18px 18px 0;
}

.knowledge-point-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  margin-bottom: 12px;
}

.knowledge-point-head strong {
  font-size: 17px;
  font-weight: 820;
}

.knowledge-point-head span {
  color: var(--muted);
  font-size: 11px;
}

.knowledge-point-grid {
  display: grid;
  grid-auto-columns: 168px;
  grid-auto-flow: column;
  gap: 12px;
  margin: 0 -18px;
  padding: 0 18px 14px;
  overflow-x: auto;
  overflow-y: hidden;
  scroll-padding: 18px;
  scroll-snap-type: x mandatory;
  overscroll-behavior-x: contain;
  -webkit-overflow-scrolling: touch;
}

.knowledge-point-grid::-webkit-scrollbar {
  height: 0;
}

.knowledge-point-card {
  position: relative;
  display: grid;
  min-width: 0;
  min-height: 92px;
  padding: 14px 14px 12px;
  overflow: hidden;
  border: 1px solid rgb(17 20 21 / 7%);
  border-radius: var(--radius-s);
  background:
    linear-gradient(180deg, rgb(255 254 254 / 95%), rgb(248 249 247 / 88%));
  box-shadow: 0 14px 28px rgb(24 30 34 / 7%);
  scroll-snap-align: start;
  text-align: left;
}

.knowledge-point-card::before {
  position: absolute;
  inset: 0 auto 0 0;
  width: 4px;
  background: currentColor;
  opacity: 0.72;
  content: "";
}

.knowledge-point-card:hover:not(.is-empty) {
  border-color: color-mix(in srgb, currentColor 42%, var(--line));
  transform: translateY(-1px);
  box-shadow: 0 13px 26px rgb(24 30 34 / 8%);
}

.knowledge-point-card > span {
  color: currentColor;
  font-size: 11px;
  font-weight: 800;
}

.knowledge-point-card strong {
  display: block;
  min-width: 0;
  margin-top: 9px;
  overflow: hidden;
  color: var(--ink);
  font-size: 17px;
  font-weight: 820;
  line-height: 1.18;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.knowledge-point-card small {
  justify-self: end;
  align-self: end;
  margin-top: 12px;
  padding: 4px 8px;
  border-radius: 999px;
  color: color-mix(in srgb, currentColor 82%, var(--ink));
  background: color-mix(in srgb, currentColor 10%, #fff);
  font-size: 11px;
  font-weight: 760;
}

.knowledge-point-card.is-empty {
  background: rgb(250 249 246 / 76%);
}

.knowledge-point-card.is-empty strong,
.knowledge-point-card.is-empty small {
  opacity: 0.62;
}

.knowledge-point-card.tone-coral { color: var(--coral); }
.knowledge-point-card.tone-blue { color: var(--blue); }
.knowledge-point-card.tone-green { color: var(--green); }
.knowledge-point-card.tone-amber { color: var(--amber); }
.knowledge-point-card.tone-violet { color: var(--violet); }

.knowledge-tools {
  display: grid;
  gap: 12px;
  margin: 16px 0 6px;
}

.chapter-test-card {
  display: grid;
  gap: 13px;
  padding: 16px;
  border: 1px solid rgb(17 20 21 / 8%);
  border-radius: var(--radius-s);
  background:
    linear-gradient(180deg, rgb(255 254 254 / 96%), rgb(238 244 241 / 86%));
  box-shadow: 0 14px 30px rgb(24 30 34 / 7%);
}

.chapter-test-copy span {
  color: var(--green);
  font-size: 12px;
  font-weight: 800;
}

.chapter-test-copy h2 {
  margin: 7px 0 0;
  font-size: 20px;
  line-height: 1.25;
}

.chapter-test-copy p {
  margin: 8px 0 0;
  color: #5f6662;
  font-size: 12px;
  line-height: 1.65;
}

.chapter-test-meta {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 7px;
}

.chapter-test-meta span {
  display: grid;
  min-height: 30px;
  place-items: center;
  border: 1px solid rgb(31 114 100 / 11%);
  border-radius: 6px;
  color: var(--green);
  background: rgb(231 241 238 / 58%);
  font-size: 11px;
  font-weight: 760;
}

.chapter-test-button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 44px;
  padding: 0 14px;
  border: 1px solid color-mix(in srgb, var(--green) 72%, #000);
  border-radius: var(--radius-s);
  color: #fff;
  background: linear-gradient(180deg, color-mix(in srgb, var(--green) 86%, #fff), var(--green));
  box-shadow: 0 13px 26px rgb(31 114 100 / 18%);
  font-weight: 800;
}

.chapter-test-button:hover {
  transform: translateY(-1px);
  box-shadow: 0 16px 30px rgb(31 114 100 / 22%);
}

.course-heading h1,
.course-heading p {
  margin: 0;
}

.course-heading h1 {
  font-size: 23px;
}

.course-heading p {
  margin-top: 5px;
  color: var(--muted);
  font-size: 12px;
}

.course-seal {
  display: grid;
  width: 52px;
  height: 52px;
  place-items: center;
  border-radius: 8px;
  color: #fff;
  background: #202321;
  font-family: Georgia, serif;
  font-size: 27px;
  box-shadow: 0 10px 22px rgb(32 35 33 / 14%);
}

.search-row {
  position: relative;
  margin: 16px 0 18px;
}

.search-row::before {
  position: absolute;
  top: 9px;
  left: 12px;
  content: "⌕";
  color: var(--muted);
  font-size: 19px;
}

.search-row input {
  width: 100%;
  height: 42px;
  padding: 0 38px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--paper);
  box-shadow: 0 6px 16px rgb(40 32 24 / 4%);
}

.search-row input:focus {
  border-color: color-mix(in srgb, var(--coral) 30%, var(--line));
  box-shadow: 0 10px 24px rgb(40 32 24 / 8%);
}

.knowledge-grid {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 10px;
}

.knowledge-card {
  min-width: 0;
  min-height: 132px;
  padding: 13px;
  border: 1px solid rgb(227 221 211 / 86%);
  border-radius: var(--radius-s);
  background: var(--paper);
  box-shadow: 0 8px 20px rgb(40 32 24 / 5%);
  text-align: left;
}

.knowledge-card:hover {
  border-color: color-mix(in srgb, currentColor 46%, var(--line));
  transform: translateY(-2px);
  box-shadow: 0 14px 28px rgb(40 32 24 / 8%);
}

.knowledge-card.coral { color: var(--coral); }
.knowledge-card.blue { color: var(--blue); }
.knowledge-card.green { color: var(--green); }
.knowledge-card.amber { color: var(--amber); }
.knowledge-card.violet { color: var(--violet); }

.knowledge-icon {
  width: 34px;
  height: 34px;
  margin-bottom: 12px;
  border: 1px solid color-mix(in srgb, currentColor 24%, transparent);
  background: color-mix(in srgb, currentColor 12%, #fff);
  font-size: 18px;
}

.knowledge-card strong,
.knowledge-card span,
.knowledge-card small {
  display: block;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.knowledge-card strong {
  color: var(--ink);
  font-size: 14px;
}

.knowledge-card span {
  margin-top: 5px;
  color: #66706a;
  opacity: 1;
  font-size: 11px;
}

.knowledge-card small {
  margin-top: 8px;
  color: #6f6a70;
  font-size: 10px;
}

.special-list {
  display: grid;
  gap: 8px;
}

.special-row {
  display: grid;
  grid-template-columns: 36px minmax(0, 1fr) auto;
  align-items: center;
  gap: 10px;
  width: 100%;
  min-height: 62px;
  padding: 9px 0;
  border: 0;
  border-bottom: 1px solid var(--line);
  background: transparent;
  text-align: left;
}

.special-row:hover {
  padding-left: 4px;
}

.special-row:last-child {
  border-bottom: 0;
}

.special-symbol {
  display: grid;
  width: 34px;
  height: 34px;
  place-items: center;
  border-radius: 7px;
  color: var(--coral);
  background: var(--coral-soft);
  font-weight: 800;
}

.special-copy strong,
.special-copy span {
  display: block;
}

.special-copy strong {
  font-size: 13px;
}

.special-copy span {
  margin-top: 4px;
  color: var(--muted);
  font-size: 10px;
}

.special-count {
  color: var(--muted);
  font-size: 11px;
}

.quiz-page {
  padding-top: 12px;
  background:
    linear-gradient(180deg, #f8f3ec 0%, #f4f0e8 100%);
}

.quiz-progress-head {
  margin-bottom: 8px;
}

.quiz-progress-head strong {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 14px;
}

.quiz-progress-head span {
  flex: 0 0 auto;
  color: var(--muted);
  font-size: 11px;
}

.quiz-progress {
  height: 5px;
  margin-bottom: 12px;
  overflow: hidden;
  border-radius: 3px;
  background: #ece5dc;
}

.quiz-progress span {
  display: block;
  height: 100%;
  background: linear-gradient(90deg, var(--coral), var(--gold), var(--crystal));
  transition: width 420ms var(--ease);
}

.question-panel {
  position: relative;
  padding: 14px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: var(--paper);
  box-shadow: 0 8px 20px rgb(40 32 24 / 6%);
}

.question-panel::before {
  position: absolute;
  top: 0;
  right: 14px;
  left: 14px;
  height: 2px;
  background: linear-gradient(90deg, transparent, rgb(180 136 69 / 45%), transparent);
  content: "";
}

.question-meta {
  display: flex;
  flex-wrap: wrap;
  gap: 5px;
  margin-bottom: 10px;
}

.meta-chip {
  padding: 4px 7px;
  border-radius: 4px;
  color: var(--blue);
  background: var(--blue-soft);
  font-size: 9px;
  font-weight: 700;
}

.meta-chip.image {
  color: var(--amber);
  background: var(--amber-soft);
}

.meta-chip.test {
  color: var(--green);
  background: var(--green-soft);
}

.test-paper-strip {
  display: grid;
  grid-template-columns: auto minmax(0, 1fr) auto;
  align-items: center;
  gap: 8px;
  margin: -2px 0 12px;
  padding: 10px 12px;
  border: 1px solid rgb(31 114 100 / 12%);
  border-radius: var(--radius-s);
  background: rgb(255 254 254 / 74%);
}

.test-paper-strip span {
  color: var(--green);
  font-size: 11px;
  font-weight: 800;
}

.test-paper-strip strong {
  color: var(--ink);
  font-size: 17px;
  font-weight: 840;
  text-align: center;
}

.test-paper-strip small {
  color: var(--muted);
  font-size: 10px;
  text-align: right;
}

.quiz-tool-strip {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
  margin: 0 0 12px;
}

.quiz-tool-strip button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 38px;
  padding: 0 11px;
  border: 1px solid rgb(17 20 21 / 7%);
  border-radius: var(--radius-s);
  background: rgb(255 254 254 / 72%);
  color: var(--muted);
  font-size: 11px;
}

.quiz-tool-strip button:hover {
  border-color: rgb(31 114 100 / 22%);
  transform: translateY(-1px);
}

.quiz-tool-strip strong {
  color: var(--ink);
  font-size: 14px;
  font-weight: 820;
}

.question-title {
  display: flex;
  align-items: flex-start;
  gap: 6px;
  margin: 0;
  font-size: 17px;
  line-height: 1.68;
}

.question-number {
  flex: 0 0 auto;
}

.content-flow {
  display: inline-flex;
  align-items: baseline;
  flex-wrap: wrap;
  gap: 5px 7px;
  min-width: 0;
}

.content-flow-stem {
  flex: 1 1 auto;
  width: auto;
}

.content-flow-option {
  align-items: center;
  width: 100%;
}

.content-text {
  min-width: 0;
  overflow-wrap: anywhere;
  white-space: pre-wrap;
}

.content-score-slot {
  display: block;
  width: 100%;
  min-height: 44px;
}

.content-score {
  display: block;
  width: auto;
  max-width: 100%;
  height: auto;
  max-height: 190px;
  margin-top: 7px;
  object-fit: contain;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: #fff;
  cursor: zoom-in;
}

.score-image {
  display: block;
  width: 100%;
  height: auto;
  max-height: 190px;
  margin-top: 12px;
  object-fit: contain;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: #fff;
  box-shadow: inset 0 0 0 1px rgb(0 0 0 / 2%);
}

button.score-image-button {
  width: 100%;
  padding: 0;
  border: 0;
  background: transparent;
}

.options-list {
  display: grid;
  gap: 8px;
  margin-top: 12px;
}

.option-button {
  display: grid;
  grid-template-columns: 30px minmax(0, 1fr);
  align-items: center;
  gap: 10px;
  width: 100%;
  min-height: 51px;
  padding: 9px 11px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: var(--paper);
  box-shadow: 0 5px 14px rgb(40 32 24 / 4%);
  text-align: left;
}

.option-button:hover:not(.selected):not(.correct):not(.wrong) {
  border-color: color-mix(in srgb, var(--blue) 28%, var(--line));
  box-shadow: 0 10px 22px rgb(40 32 24 / 7%);
  transform: translateY(-1px);
}

.option-key {
  display: grid;
  width: 27px;
  height: 27px;
  place-items: center;
  border-radius: 50%;
  color: #5d625c;
  background: var(--surface-strong);
  font-size: 11px;
  font-weight: 800;
}

.option-copy {
  min-width: 0;
  overflow-wrap: anywhere;
  font-size: 13px;
  line-height: 1.45;
}

.option-copy img {
  display: block;
  width: auto;
  max-width: 100%;
  height: auto;
  max-height: 110px;
  object-fit: contain;
}

.option-copy .content-score {
  max-height: 110px;
  border-color: rgb(17 20 21 / 9%);
}

.option-button.selected {
  border-color: var(--blue);
  background: linear-gradient(180deg, #edf5f7, var(--blue-soft));
  box-shadow: 0 10px 24px rgb(53 93 119 / 10%);
}

.option-button.selected .option-key {
  color: #fff;
  background: var(--blue);
}

.option-button.correct {
  border-color: #61aa96;
  background: linear-gradient(180deg, #f2fbf7, var(--green-soft));
}

.option-button.correct .option-key {
  color: #fff;
  background: var(--green);
}

.option-button.wrong {
  border-color: #e07a7a;
  background: #fff2f2;
}

.option-button.wrong .option-key {
  color: #fff;
  background: var(--danger);
}

.answer-panel {
  margin-top: 12px;
  padding: 13px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: rgb(255 252 248 / 76%);
}

.result-head strong {
  font-size: 13px;
}

.result-head strong.ok { color: var(--green); }
.result-head strong.bad { color: var(--danger); }
.result-head strong.pending { color: var(--amber); }

.answer-panel p {
  margin: 8px 0 0;
  color: #615d63;
  font-size: 12px;
  line-height: 1.6;
}

.video-entry {
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr) auto;
  align-items: center;
  gap: 9px;
  width: 100%;
  min-height: 58px;
  margin-top: 11px;
  padding: 9px 10px;
  border: 1px solid rgb(223 228 224 / 72%);
  border-radius: var(--radius-s);
  background: #fffaf1;
  text-align: left;
}

.video-entry:hover {
  transform: translateY(-1px);
  box-shadow: 0 10px 24px rgb(40 32 24 / 8%);
}

.play-symbol {
  display: grid;
  width: 36px;
  height: 36px;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: var(--coral);
  font-size: 13px;
}

.video-entry strong,
.video-entry span {
  display: block;
}

.video-entry strong {
  font-size: 12px;
}

.video-entry span {
  margin-top: 3px;
  color: var(--muted);
  font-size: 10px;
}

.video-entry b {
  color: var(--coral);
  font-size: 18px;
}

.quiz-actions {
  display: grid;
  grid-template-columns: 72px minmax(0, 1fr);
  gap: 8px;
  margin-top: 13px;
}

.next-action-group {
  display: grid;
  gap: 5px;
  min-width: 0;
}

.quiz-hint {
  display: grid;
  min-height: 16px;
  place-items: center;
  color: var(--muted);
  font-size: 11px;
}

.favorite-button {
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--paper);
  color: #6f6970;
  font-size: 18px;
}

.favorite-button.active {
  color: var(--amber);
  border-color: #e8c96d;
  background: var(--amber-soft);
}

.video-page {
  padding: 0 0 24px;
  background: linear-gradient(180deg, #f7f3ed 0%, #f2eee6 100%);
}

.protected-player {
  position: relative;
  width: 100%;
  aspect-ratio: 16 / 10;
  overflow: hidden;
  background: var(--void);
  isolation: isolate;
  box-shadow: 0 14px 34px rgb(9 11 13 / 18%);
}

.protected-player video,
.video-poster {
  position: absolute;
  inset: 0;
  display: block;
  width: 100%;
  height: 100%;
  object-fit: contain;
  background: #161516;
}

.video-poster.empty {
  display: grid;
  place-items: center;
  color: #d8d2d6;
  font-family: Georgia, serif;
  font-size: 68px;
}

.player-tint {
  position: absolute;
  inset: 0;
  z-index: 2;
  background:
    linear-gradient(180deg, rgb(9 11 13 / 10%), rgb(9 11 13 / 38%)),
    rgb(17 16 17 / 20%);
  pointer-events: none;
}

.player-center {
  position: absolute;
  z-index: 4;
  top: 50%;
  left: 50%;
  display: grid;
  width: 56px;
  height: 56px;
  place-items: center;
  border: 1px solid rgb(255 255 255 / 75%);
  border-radius: 50%;
  color: #fff;
  background: rgb(18 17 18 / 64%);
  backdrop-filter: blur(8px);
  transform: translate(-50%, -50%);
  font-size: 20px;
}

.player-center:hover {
  background: rgb(247 242 234 / 18%);
  transform: translate(-50%, -50%) scale(1.04);
}

.player-status {
  position: absolute;
  z-index: 4;
  right: 11px;
  bottom: 10px;
  left: 11px;
  display: flex;
  align-items: center;
  justify-content: space-between;
  color: #fff;
  font-size: 10px;
}

.secure-watermarks {
  position: absolute;
  z-index: 3;
  inset: -20%;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-auto-rows: 56px;
  align-items: center;
  opacity: 0.24;
  transform: rotate(-22deg);
  pointer-events: none;
}

.secure-watermarks span {
  color: #fff;
  font-size: 9px;
  text-align: center;
  white-space: nowrap;
}

.recording-cover {
  position: absolute;
  z-index: 8;
  inset: 0;
  display: none;
  place-items: center;
  color: #fff;
  background: #171617;
  text-align: center;
}

.recording-cover.visible {
  display: grid;
}

.recording-cover strong,
.recording-cover span {
  display: block;
}

.recording-cover strong {
  font-size: 14px;
}

.recording-cover span {
  margin-top: 7px;
  color: #bcb5ba;
  font-size: 10px;
}

.lesson-body {
  padding: 17px 18px 0;
}

.lesson-body h1 {
  margin: 7px 0 8px;
  font-size: 19px;
  line-height: 1.45;
}

.teacher-strip {
  display: grid;
  grid-template-columns: 38px minmax(0, 1fr) auto;
  align-items: center;
  gap: 9px;
  margin: 18px 0;
  padding: 12px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: rgb(255 252 248 / 78%);
}

.teacher-avatar {
  display: grid;
  width: 38px;
  height: 38px;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: #202321;
  font-size: 12px;
  font-weight: 800;
}

.teacher-copy strong,
.teacher-copy span {
  display: block;
}

.teacher-copy strong {
  font-size: 12px;
}

.teacher-copy span {
  margin-top: 4px;
  color: var(--muted);
  font-size: 10px;
}

.teacher-strip > span {
  color: var(--green);
  font-size: 10px;
  font-weight: 700;
}

.lesson-section {
  margin-top: 20px;
}

.lesson-section h2 {
  margin: 0 0 10px;
  font-size: 15px;
}

.lesson-summary {
  margin: 0;
  color: #5f5a60;
  font-size: 12px;
  line-height: 1.75;
}

.lesson-list {
  overflow: hidden;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: rgb(255 252 248 / 76%);
}

.lesson-row {
  min-height: 48px;
  padding: 0 12px;
  border-bottom: 1px solid var(--line);
  font-size: 11px;
}

.lesson-row span:first-child {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}

.lesson-row span:last-child {
  flex: 0 0 auto;
  color: var(--muted);
}

.empty-page,
.profile-page {
  display: grid;
  align-content: start;
  gap: 14px;
}

.empty-visual {
  display: grid;
  width: 70px;
  height: 70px;
  margin: 42px auto 4px;
  place-items: center;
  border-radius: 50%;
  color: var(--blue);
  background: var(--blue-soft);
  font-family: Georgia, serif;
  font-size: 38px;
}

.empty-page h2,
.empty-page p {
  margin: 0;
  text-align: center;
}

.empty-page h2 {
  font-size: 18px;
}

.empty-page p {
  color: var(--muted);
  font-size: 12px;
  line-height: 1.6;
}

.profile-banner {
  margin: -16px -18px 8px;
  padding: 22px 18px;
  color: #fff;
  background: linear-gradient(135deg, #1f2324, #59432f);
}

.profile-banner strong,
.profile-banner span {
  display: block;
}

.profile-banner strong {
  font-size: 20px;
}

.profile-banner span {
  margin-top: 5px;
  color: #e7d9c4;
  font-size: 11px;
}

.profile-stat-line {
  padding: 14px 0;
  border-bottom: 1px solid var(--line);
}

.profile-stat-line strong {
  color: var(--coral);
  font-size: 18px;
}

.bottom-nav {
  display: grid;
  grid-template-columns: repeat(4, minmax(0, 1fr));
  align-items: stretch;
  border-top: 1px solid var(--line);
  background: rgb(255 250 243 / 94%);
  backdrop-filter: blur(10px);
  box-shadow: 0 -8px 22px rgb(40 32 24 / 5%);
}

.bottom-nav.hidden {
  display: none;
}

.nav-button {
  display: grid;
  grid-template-rows: 24px 17px;
  align-content: center;
  justify-items: center;
  min-width: 0;
  padding: 0 3px;
  border: 0;
  color: #7c817a;
  background: transparent;
  font-size: 10px;
}

.nav-button .nav-icon {
  display: grid;
  width: 24px;
  height: 24px;
  place-items: center;
  font-family: Georgia, serif;
  font-size: 20px;
  line-height: 1;
}

.nav-button.active {
  color: var(--coral);
}

.nav-button.active .nav-icon {
  transform: translateY(-1px);
}

.nav-button:hover {
  color: var(--ink);
}

.capture-shield {
  position: absolute;
  z-index: 80;
  inset: 0;
  display: none;
  place-items: center;
  align-content: center;
  gap: 10px;
  color: #fff;
  background: #171617;
  text-align: center;
}

.capture-shield.visible {
  display: grid;
}

.shield-mark {
  display: grid;
  width: 60px;
  height: 60px;
  place-items: center;
  border: 1px solid #75695b;
  border-radius: 50%;
  color: #e8d7bd;
  font-family: Georgia, "Songti SC", serif;
  font-size: 18px;
}

.capture-shield strong {
  font-size: 14px;
}

.app-toast {
  position: absolute;
  z-index: 90;
  right: 20px;
  bottom: 78px;
  left: 20px;
  padding: 10px 12px;
  opacity: 0;
  border-radius: var(--radius-s);
  color: #fff;
  background: rgb(32 35 33 / 92%);
  pointer-events: none;
  transform: translateY(6px);
  transition: opacity 150ms ease, transform 150ms ease;
  text-align: center;
  font-size: 11px;
}

.app-toast.visible {
  opacity: 1;
  transform: translateY(0);
}

.preview-panel {
  display: grid;
  gap: 12px;
}

.preview-section {
  padding: 18px;
  border: 1px solid var(--line);
  border-radius: var(--radius-m);
  background: rgb(255 250 243 / 88%);
  box-shadow: 0 12px 28px rgb(40 32 24 / 8%);
}

.preview-section h1,
.preview-section h2,
.preview-section p {
  margin-top: 0;
}

.preview-section h1 {
  margin-bottom: 8px;
  font-size: 24px;
}

.preview-section h2 {
  margin-bottom: 12px;
  font-size: 15px;
}

.panel-copy,
.note-section p {
  margin-bottom: 16px;
  color: var(--muted);
  font-size: 12px;
  line-height: 1.65;
}

.route-switcher {
  display: grid;
  grid-template-columns: repeat(2, minmax(0, 1fr));
  gap: 8px;
}

.route-switcher button,
.shield-test {
  min-height: 38px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: var(--paper);
  font-size: 12px;
  font-weight: 680;
}

.route-switcher button:hover,
.route-switcher button.active {
  color: #fff;
  border-color: var(--void);
  background: var(--void);
}

.developer-link {
  display: inline-flex;
  align-items: center;
  justify-content: center;
  width: 100%;
  min-height: 38px;
  margin-top: 10px;
  border: 1px solid color-mix(in srgb, var(--green) 26%, var(--line));
  border-radius: var(--radius-s);
  color: var(--green);
  background: rgb(255 252 248 / 74%);
  text-decoration: none;
  font-size: 12px;
  font-weight: 820;
}

.developer-link:hover {
  border-color: color-mix(in srgb, var(--green) 44%, var(--line));
  background: var(--green-soft);
  box-shadow: 0 10px 24px rgb(47 43 38 / 7%);
  transform: translateY(-1px);
}

.state-list {
  display: grid;
  grid-template-columns: 90px minmax(0, 1fr);
  gap: 9px 12px;
  margin: 0;
  font-size: 12px;
}

.state-list dt {
  color: var(--muted);
}

.state-list dd {
  margin: 0;
  overflow-wrap: anywhere;
}

.security-heading {
  display: flex;
  align-items: center;
  gap: 8px;
}

.security-heading h2 {
  margin: 0;
}

.security-dot {
  width: 9px;
  height: 9px;
  border-radius: 50%;
  background: var(--green);
  box-shadow: 0 0 0 4px var(--green-soft);
}

.security-list {
  margin: 14px 0;
  padding-left: 19px;
  color: #555b55;
  font-size: 12px;
  line-height: 1.9;
}

.watermark-field {
  display: grid;
  gap: 6px;
  margin-bottom: 9px;
}

.watermark-field span {
  color: var(--muted);
  font-size: 10px;
}

.watermark-field input {
  width: 100%;
  height: 38px;
  padding: 0 10px;
  border: 1px solid var(--line);
  border-radius: var(--radius-s);
  background: var(--paper);
}

.shield-test {
  width: 100%;
  color: var(--green);
  border-color: #91ccbc;
  background: var(--green-soft);
}

/* Xiaomi Auto inspired visual polish: dark cockpit, floating panels, restrained accent. */
body {
  background:
    linear-gradient(135deg, #0b0e0f 0%, #171b1c 42%, #eef1ee 42.3%, #dfe4df 100%);
}

.device {
  background: linear-gradient(180deg, #07090a 0%, #141718 100%);
  box-shadow:
    0 34px 76px rgb(4 8 10 / 38%),
    inset 0 1px 0 rgb(255 255 255 / 9%);
}

.device-screen {
  background:
    linear-gradient(180deg, rgb(255 255 255 / 2%) 0%, transparent 34%),
    #0d1112;
}

.system-bar,
.mini-header {
  color: rgb(238 242 239 / 72%);
  background: #0d1112;
}

.mini-header.with-line {
  border-bottom-color: rgb(255 255 255 / 6%);
}

.header-icon {
  color: rgb(238 242 239 / 70%);
}

.header-icon:hover {
  color: #fff;
  background: rgb(255 255 255 / 7%);
}

.mobile-app {
  background: #0d1112;
}

.subjects-page,
.knowledge-page,
.quiz-page,
.profile-page {
  background:
    linear-gradient(180deg, #101516 0%, #0d1112 100%);
}

.page-heading h2,
.section-label,
.knowledge-wordmark strong,
.header-title {
  color: #f4f7f4;
}

.page-heading p,
.knowledge-wordmark span {
  color: rgb(244 247 244 / 58%);
}

.course-ad-carousel,
.home-hero,
.knowledge-daily-hero {
  border: 1px solid rgb(255 255 255 / 8%);
  border-radius: 18px;
  background:
    linear-gradient(135deg, #181d1e 0%, #101415 54%, #253330 100%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 9%),
    0 22px 44px rgb(0 0 0 / 28%);
}

.course-ad-carousel {
  margin: 0;
}

.course-ad-carousel::before {
  background:
    linear-gradient(90deg, transparent, rgb(114 214 199 / 13%), transparent),
    repeating-linear-gradient(90deg, transparent 0 28px, rgb(255 255 255 / 4%) 29px, transparent 30px 58px);
}

.course-ad-carousel::after {
  display: none;
}

.course-ad-copy span,
.course-ad-copy p,
.hero-copy span,
.hero-copy p {
  color: rgb(244 247 244 / 66%);
  letter-spacing: 0;
}

.course-ad-copy h1,
.hero-copy h1 {
  color: #f8fbf8;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-weight: 780;
}

.course-ad-action,
.hero-action,
.chapter-test-button,
.primary-command {
  border-color: rgb(119 230 209 / 24%);
  color: #07100f;
  background: linear-gradient(180deg, #ccfff4 0%, #83dccf 100%);
  box-shadow: 0 16px 34px rgb(89 224 202 / 18%);
}

.course-ad-action::after,
.hero-action b {
  color: rgb(7 16 15 / 72%);
}

.course-ad-dots span {
  background: rgb(244 247 244 / 26%);
}

@keyframes course-ad-dot {
  0%, 27% { background: #83dccf; transform: scale(1.28); }
  33%, 100% { background: rgb(244 247 244 / 26%); transform: scale(1); }
}

.continue-band,
.chapter-test-card {
  border-color: rgb(255 255 255 / 8%);
  background:
    linear-gradient(180deg, rgb(255 255 255 / 94%), rgb(238 243 240 / 90%));
  box-shadow: 0 18px 38px rgb(0 0 0 / 18%);
}

.path-list {
  gap: 8px;
  border: 0;
  background: transparent;
}

.path-row {
  min-height: 64px;
  padding: 10px 12px;
  border: 1px solid rgb(15 21 22 / 6%);
  border-radius: 14px;
  background: rgb(250 252 249 / 95%);
  box-shadow: 0 10px 24px rgb(0 0 0 / 8%);
}

.path-row:hover {
  background: #fff;
  transform: translateY(-1px);
}

.path-row.active {
  border-color: rgb(119 230 209 / 26%);
  background:
    linear-gradient(90deg, rgb(131 220 207 / 18%), rgb(250 252 249 / 98%) 58%);
}

.path-index {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  border-radius: 50%;
  color: #0f1918;
  background: rgb(131 220 207 / 22%);
  font-family: Georgia, "Times New Roman", serif;
}

.subject-path-list {
  margin-top: 4px;
}

.knowledge-topbar {
  color: #f4f7f4;
  background: transparent;
}

.knowledge-bar-icon,
.knowledge-pill {
  color: rgb(244 247 244 / 78%);
  background: rgb(255 255 255 / 7%);
}

.knowledge-bar-icon:hover {
  color: #fff;
  background: rgb(255 255 255 / 12%);
}

.knowledge-point-head strong {
  color: #f4f7f4;
}

.knowledge-point-head span {
  color: rgb(244 247 244 / 55%);
}

.knowledge-point-card {
  min-height: 96px;
  border-color: rgb(255 255 255 / 8%);
  color: #83dccf;
  background:
    linear-gradient(180deg, rgb(255 255 255 / 10%), rgb(255 255 255 / 5%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 8%),
    0 18px 34px rgb(0 0 0 / 20%);
}

.knowledge-point-card strong {
  color: #f4f7f4;
}

.knowledge-point-card small {
  color: rgb(244 247 244 / 78%);
  background: rgb(255 255 255 / 8%);
}

.knowledge-point-card.is-empty {
  background: rgb(255 255 255 / 5%);
}

.chapter-test-copy h2 {
  color: #101516;
}

.quiz-progress {
  background: rgb(255 255 255 / 10%);
}

.quiz-progress span,
.progress-track span {
  background: linear-gradient(90deg, #83dccf, #d7f5ee);
}

.test-paper-strip,
.quiz-tool-strip button {
  border-color: rgb(255 255 255 / 8%);
  background:
    linear-gradient(180deg, rgb(255 255 255 / 12%), rgb(255 255 255 / 6%));
  color: rgb(244 247 244 / 72%);
}

.test-paper-strip strong,
.quiz-tool-strip strong {
  color: #f4f7f4;
}

.test-paper-strip span {
  color: #83dccf;
}

.question-panel,
.option-button,
.answer-panel,
.video-entry {
  border-color: rgb(15 21 22 / 7%);
  border-radius: 16px;
  background: #f8faf6;
  box-shadow: 0 18px 34px rgb(0 0 0 / 15%);
}

.question-panel::before {
  background: linear-gradient(90deg, transparent, rgb(131 220 207 / 62%), transparent);
}

.meta-chip {
  border-radius: 999px;
  color: #1d5f59;
  background: rgb(131 220 207 / 18%);
}

.option-button:hover:not(.selected):not(.correct):not(.wrong) {
  border-color: rgb(35 151 138 / 30%);
  box-shadow: 0 16px 28px rgb(0 0 0 / 14%);
}

.option-key,
.favorite-button {
  background: #eef3ef;
}

.option-button.selected {
  border-color: #43b9aa;
  background: linear-gradient(180deg, #f0fffb, #dcf7f1);
}

.option-button.selected .option-key,
.option-button.correct .option-key,
.play-symbol {
  background: #1a9c8d;
}

.bottom-nav {
  border-top-color: rgb(255 255 255 / 7%);
  background: rgb(13 17 18 / 92%);
  box-shadow: 0 -18px 34px rgb(0 0 0 / 26%);
}

.nav-button {
  color: rgb(244 247 244 / 54%);
}

.nav-button.active {
  color: #83dccf;
}

.nav-button:hover {
  color: #f4f7f4;
}

.preview-panel {
  border-color: rgb(255 255 255 / 9%);
  background: rgb(255 255 255 / 74%);
  backdrop-filter: blur(18px);
}

@media (prefers-reduced-motion: reduce) {
  *,
  *::before,
  *::after {
    scroll-behavior: auto !important;
    transition-duration: 0.01ms !important;
    animation-duration: 0.01ms !important;
    animation-iteration-count: 1 !important;
  }
}

.image-viewer {
  position: absolute;
  z-index: 100;
  inset: 0;
  display: grid;
  place-items: center;
  padding: 18px;
  background: rgb(20 18 19 / 92%);
}

.image-viewer[hidden] {
  display: none;
}

.image-viewer img {
  display: block;
  width: min(100%, 560px);
  max-width: 100%;
  height: auto;
  max-height: 54%;
  object-fit: contain;
  background: #fff;
  border-radius: 8px;
  box-shadow: 0 14px 32px rgb(0 0 0 / 35%);
}

.viewer-close {
  position: absolute;
  z-index: 101;
  top: 12px;
  right: 12px;
  display: grid;
  width: 40px;
  height: 40px;
  padding: 0;
  place-items: center;
  border: 1px solid #777176;
  border-radius: 50%;
  color: #fff;
  background: #262326;
  font-size: 26px;
}

@media (max-width: 920px) {
  .preview-shell {
    grid-template-columns: 1fr;
    padding: 16px;
  }

  .device {
    position: static;
    margin: 0 auto;
    height: min(844px, calc(100vh - 32px));
  }

  .preview-panel {
    width: min(100%, 390px);
    margin: 0 auto;
  }
}

@media (max-width: 760px) {
  .showcase-grid {
    grid-template-columns: 1fr;
  }

  .knowledge-hero {
    min-height: 228px;
  }

  .knowledge-hero h1 {
    margin-top: 56px;
    font-size: 28px;
  }

  .hero-ghost {
    top: 80px;
    font-size: 38px;
  }
}

@media (max-width: 480px) {
  .preview-shell {
    display: grid;
    min-height: 100vh;
    padding: 16px;
  }

  .device {
    width: 390px;
    max-width: 100%;
    height: min(844px, calc(100vh - 32px));
    min-height: 720px;
    padding: 12px;
    border-radius: 34px;
    box-shadow: 0 18px 48px rgba(15, 23, 42, 0.24);
  }

  .device-screen {
    border-radius: 26px;
  }

  .preview-panel {
    display: grid;
  }

  .knowledge-hero {
    margin: -16px -18px 0;
    min-height: 220px;
    padding: 16px 16px 24px;
  }

  .hero-topline {
    margin-bottom: 14px;
    font-size: 11px;
  }

  .knowledge-hero h1 {
    margin-top: 50px;
    font-size: 26px;
  }

  .hero-ghost {
    top: 78px;
    font-size: 32px;
  }

  .showcase-grid {
    gap: 12px;
    margin-top: -18px;
  }

  .showcase-phone {
    padding: 7px;
  }

  .showcase-shell {
    min-height: 404px;
  }
}

/* Soft ivory / olive polish inspired by the user's reference screenshots. */
:root {
  --ink: #262826;
  --muted: #7d8177;
  --line: #e5e3dc;
  --paper: #fffdf8;
  --surface: #f7f4ee;
  --surface-strong: #e9ebe3;
  --coral: #9cae5f;
  --coral-dark: #819448;
  --coral-soft: #eef3dd;
  --green: #8ca253;
  --green-soft: #edf3de;
  --blue: #8b9d74;
  --blue-soft: #eef3e5;
  --amber: #b39a57;
  --amber-soft: #f3eddc;
  --violet: #8c8596;
  --violet-soft: #f0edf2;
  --danger: #c16f63;
  --gold: #b59c5a;
  --crystal: #b3c882;
  --shadow: 0 16px 34px rgb(64 72 52 / 10%);
}

body {
  background:
    radial-gradient(circle at 10% 10%, rgb(209 220 186 / 36%) 0 16%, transparent 34%),
    radial-gradient(circle at 88% 8%, rgb(229 234 221 / 70%) 0 14%, transparent 30%),
    linear-gradient(135deg, #f9f7f2 0%, #f6f3ec 48%, #eef2ea 100%);
}

.device {
  background: linear-gradient(180deg, #202321 0%, #111413 100%);
  box-shadow:
    0 28px 70px rgb(27 30 24 / 22%),
    inset 0 1px 0 rgb(255 255 255 / 8%);
}

.device-screen {
  background:
    linear-gradient(180deg, rgb(255 255 255 / 62%) 0%, rgb(247 244 238 / 0%) 36%),
    var(--surface);
}

.system-bar,
.mini-header {
  background: linear-gradient(180deg, rgb(255 255 255 / 82%), rgb(247 244 238 / 92%));
}

.mobile-app {
  background:
    radial-gradient(circle at top, rgb(225 232 213 / 48%) 0, transparent 24%),
    var(--surface);
}

.subjects-page,
.knowledge-page,
.quiz-page,
.profile-page {
  background: linear-gradient(180deg, rgb(249 247 242 / 96%) 0%, rgb(240 243 236 / 96%) 100%);
}

.page-heading h2,
.section-label,
.knowledge-wordmark strong,
.header-title {
  color: #2a2c29;
}

.page-heading p,
.knowledge-wordmark span {
  color: var(--muted);
}

.course-ad-carousel,
.home-hero,
.knowledge-daily-hero {
  margin: 0 -18px;
  border: 1px solid rgb(255 255 255 / 75%);
  border-radius: 26px;
  background: linear-gradient(135deg, #fdfbf7 0%, #f3f2ec 58%, #e8eddc 100%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 90%),
    0 18px 34px rgb(74 83 57 / 10%);
}

.course-ad-carousel::before {
  background:
    linear-gradient(90deg, transparent, rgb(172 192 123 / 24%), transparent),
    repeating-linear-gradient(90deg, transparent 0 28px, rgb(80 92 59 / 5%) 29px, transparent 30px 58px);
}

.course-ad-carousel::after {
  border-color: rgb(156 174 95 / 16%);
}

.course-ad-copy span,
.course-ad-copy p,
.hero-copy span,
.hero-copy p {
  color: rgb(63 68 58 / 62%);
}

.course-ad-copy h1,
.hero-copy h1 {
  color: #2a2c29;
  font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang SC", "Microsoft YaHei", sans-serif;
  font-weight: 820;
}

.course-ad-action,
.hero-action,
.chapter-test-button,
.primary-command {
  border-color: rgb(140 162 83 / 22%);
  color: #283024;
  background: linear-gradient(180deg, #f9fdf2 0%, #d9e6b0 100%);
  box-shadow: 0 14px 30px rgb(140 162 83 / 18%);
}

.course-ad-action::after,
.hero-action b {
  color: rgb(40 48 36 / 70%);
}

.course-ad-dots span {
  background: rgb(110 121 84 / 24%);
}

@keyframes course-ad-dot {
  0%, 27% { background: #8ca253; transform: scale(1.24); }
  33%, 100% { background: rgb(110 121 84 / 24%); transform: scale(1); }
}

.continue-band,
.chapter-test-card {
  border-color: rgb(255 255 255 / 82%);
  background: linear-gradient(180deg, rgb(255 255 255 / 94%), rgb(245 247 240 / 88%));
  box-shadow: 0 16px 34px rgb(79 88 61 / 10%);
}

.path-list {
  gap: 8px;
  border: 0;
  background: transparent;
}

.path-row {
  min-height: 64px;
  padding: 10px 12px;
  border: 1px solid rgb(224 228 219 / 76%);
  border-radius: 16px;
  background: rgb(253 253 250 / 94%);
  box-shadow: 0 10px 24px rgb(74 83 57 / 8%);
}

.path-row:hover {
  background: #fff;
  transform: translateY(-1px);
}

.path-row.active {
  border-color: rgb(156 174 95 / 22%);
  background: linear-gradient(90deg, rgb(207 219 164 / 32%), rgb(255 255 255 / 96%) 58%);
}

.path-index {
  display: grid;
  width: 32px;
  height: 32px;
  place-items: center;
  border-radius: 50%;
  color: #5e664f;
  background: rgb(196 211 146 / 26%);
  font-family: Georgia, "Times New Roman", serif;
}

.knowledge-topbar {
  color: #2a2c29;
  background: transparent;
}

.knowledge-bar-icon,
.knowledge-pill {
  color: rgb(54 60 46 / 74%);
  background: rgb(255 255 255 / 76%);
}

.knowledge-bar-icon:hover {
  color: #20231f;
  background: #fff;
}

.knowledge-point-head strong {
  color: #2a2c29;
}

.knowledge-point-head span {
  color: var(--muted);
}

.knowledge-point-card {
  min-height: 96px;
  border-color: rgb(224 228 219 / 80%);
  color: #8ca253;
  background: linear-gradient(180deg, rgb(255 255 255 / 96%), rgb(247 249 243 / 92%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 84%),
    0 14px 30px rgb(74 83 57 / 8%);
}

.knowledge-point-card strong {
  color: #2a2c29;
}

.knowledge-point-card small {
  color: rgb(61 68 55 / 84%);
  background: rgb(156 174 95 / 10%);
}

.knowledge-point-card.is-empty {
  background: rgb(250 249 246 / 84%);
}

.chapter-test-copy h2 {
  color: #2a2c29;
}

.quiz-progress {
  background: rgb(226 228 220 / 82%);
}

.quiz-progress span,
.progress-track span {
  background: linear-gradient(90deg, #9cae5f, #d9e6b0);
}

.test-paper-strip,
.quiz-tool-strip button {
  border-color: rgb(224 228 219 / 80%);
  background: linear-gradient(180deg, rgb(255 255 255 / 92%), rgb(247 249 243 / 90%));
  color: rgb(82 88 74 / 78%);
}

.test-paper-strip strong,
.quiz-tool-strip strong {
  color: #2a2c29;
}

.test-paper-strip span {
  color: #8ca253;
}

.question-panel,
.option-button,
.answer-panel,
.video-entry {
  border-color: rgb(224 228 219 / 82%);
  border-radius: 18px;
  background: rgb(255 255 255 / 94%);
  box-shadow: 0 14px 28px rgb(74 83 57 / 8%);
}

.question-panel::before {
  background: linear-gradient(90deg, transparent, rgb(156 174 95 / 58%), transparent);
}

.meta-chip {
  border-radius: 999px;
  color: #55705d;
  background: rgb(196 211 146 / 18%);
}

.option-button:hover:not(.selected):not(.correct):not(.wrong) {
  border-color: rgb(140 162 83 / 28%);
  box-shadow: 0 14px 26px rgb(74 83 57 / 12%);
}

.option-key,
.favorite-button {
  background: #eef2e3;
}

.option-button.selected {
  border-color: #8ca253;
  background: linear-gradient(180deg, #f8fbef, #e8f1d2);
}

.option-button.selected .option-key,
.option-button.correct .option-key,
.play-symbol {
  background: #8ca253;
}

.bottom-nav {
  border-top-color: rgb(224 228 219 / 88%);
  background: rgb(255 255 255 / 94%);
  box-shadow: 0 -14px 28px rgb(74 83 57 / 8%);
}

.nav-button {
  color: rgb(104 110 95 / 72%);
}

.nav-button.active {
  color: #8ca253;
}

.nav-button:hover {
  color: #2a2c29;
}

.profile-banner {
  color: #293024;
  background: linear-gradient(135deg, #f4f7ec 0%, #e7efcf 100%);
}

.profile-banner span {
  color: rgb(68 74 58 / 72%);
}

.preview-panel {
  border-color: rgb(224 228 219 / 90%);
  background: rgb(255 255 255 / 80%);
  backdrop-filter: blur(18px);
}

/* Reference mockup pass: clean white learning app with emerald accents. */
:root {
  --mock-ink: #111514;
  --mock-muted: #8b918d;
  --mock-faint: #f3f5f3;
  --mock-line: #ecefed;
  --mock-green: #16826f;
  --mock-green-dark: #0f6b5c;
  --mock-red: #ef4b4b;
  --mock-card-shadow: 0 12px 34px rgb(15 30 26 / 7%);
}

.device-screen {
  grid-template-rows: 34px minmax(0, 1fr) 78px;
  background: #fbfcfb;
}

.device-screen.immersive {
  grid-template-rows: 34px minmax(0, 1fr) 0;
}

.mini-header {
  display: none;
}

.system-bar {
  grid-template-columns: 1fr 1fr;
  padding: 0 22px;
  color: #0b0f0e;
  background: #fbfcfb;
  font-size: 13px;
  font-weight: 850;
}

.system-island {
  display: none;
}

.system-icons {
  font-size: 12px;
  color: #0b0f0e;
}

.mobile-app,
.subjects-page,
.knowledge-page,
.quiz-page {
  background: #fbfcfb;
}

.page {
  padding: 18px 20px 22px;
}

.home-greeting {
  display: flex;
  align-items: flex-start;
  justify-content: space-between;
  gap: 14px;
  margin: 8px 0 22px;
}

.home-greeting h1,
.home-greeting p,
.section-heading h2,
.study-card h2,
.chapter-hero h1,
.question-title {
  margin: 0;
}

.home-greeting h1 {
  color: var(--mock-ink);
  font-size: 22px;
  line-height: 1.1;
  font-weight: 900;
}

.home-greeting h1 span {
  color: var(--mock-green);
}

.home-greeting p {
  margin-top: 8px;
  color: #171b19;
  font-size: 13px;
  font-weight: 760;
}

.checkin-button {
  display: grid;
  min-width: 42px;
  padding: 0;
  border: 0;
  color: #171b19;
  background: transparent;
  font-size: 11px;
  font-weight: 760;
}

.checkin-button span {
  font-size: 20px;
  line-height: 1;
}

.practice-banner {
  position: relative;
  min-height: 154px;
  overflow: hidden;
  margin: 0 0 22px;
  padding: 28px 24px;
  border-radius: 12px;
  color: #fff;
  background:
    linear-gradient(90deg, rgb(2 5 5 / 92%) 0%, rgb(4 7 7 / 94%) 54%, rgb(20 22 22 / 96%) 100%);
  box-shadow: 0 16px 30px rgb(8 12 12 / 16%);
}

.practice-banner h2 {
  position: relative;
  z-index: 2;
  margin: 0;
  font-size: 24px;
  line-height: 1.38;
  font-weight: 900;
  letter-spacing: 0;
}

.practice-banner p {
  position: relative;
  z-index: 2;
  margin: 12px 0 0;
  color: rgb(255 255 255 / 62%);
  font-size: 10px;
  font-weight: 800;
  letter-spacing: 0.08em;
}

.piano-shine {
  position: absolute;
  top: -22px;
  right: -20px;
  width: 210px;
  height: 118px;
  background:
    linear-gradient(158deg, transparent 0 22%, rgb(255 255 255 / 38%) 23% 30%, transparent 31% 100%),
    repeating-linear-gradient(105deg, rgb(255 255 255 / 9%) 0 8px, rgb(255 255 255 / 2%) 8px 16px);
  filter: blur(0.2px);
  opacity: 0.82;
  transform: skewX(-18deg);
}

.banner-dots {
  position: absolute;
  bottom: 14px;
  left: 50%;
  display: flex;
  gap: 6px;
  transform: translateX(-50%);
}

.banner-dots span {
  width: 6px;
  height: 6px;
  border-radius: 50%;
  background: rgb(255 255 255 / 48%);
}

.banner-dots span:first-child {
  background: #3ac2a8;
}

.section-heading {
  margin: 0 0 14px;
}

.section-heading h2,
.study-card h2 {
  color: var(--mock-ink);
  font-size: 18px;
  font-weight: 900;
}

.subject-tile-grid {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px 12px;
}

.subject-tile {
  display: grid;
  min-width: 0;
  min-height: 132px;
  place-items: center;
  align-content: center;
  padding: 16px 8px 14px;
  border: 1px solid rgb(236 239 237 / 78%);
  border-radius: 10px;
  background: #fff;
  box-shadow: var(--mock-card-shadow);
  text-align: center;
}

.subject-tile:hover:not(.is-coming) {
  transform: translateY(-2px);
  box-shadow: 0 16px 38px rgb(15 30 26 / 10%);
}

.subject-bubble {
  display: grid;
  width: 54px;
  height: 54px;
  margin-bottom: 12px;
  place-items: center;
  border-radius: 50%;
  color: var(--tile-color, var(--mock-green));
  background: var(--tile-bg, #e9f8f4);
  font-size: 28px;
  font-weight: 900;
}

.subject-tile strong {
  color: var(--mock-ink);
  font-size: 14px;
  font-weight: 900;
}

.subject-tile small {
  margin-top: 8px;
  color: var(--mock-muted);
  font-size: 11px;
  font-weight: 760;
}

.subject-tile.tone-green { --tile-color: #18916f; --tile-bg: #e5f6f1; }
.subject-tile.tone-violet { --tile-color: #8359ee; --tile-bg: #f0eaff; }
.subject-tile.tone-orange { --tile-color: #ff8c12; --tile-bg: #fff0df; }
.subject-tile.tone-blue { --tile-color: #426fff; --tile-bg: #e9efff; }
.subject-tile.tone-amber { --tile-color: #f19118; --tile-bg: #fff2df; }
.subject-tile.tone-navy { --tile-color: #0c3550; --tile-bg: #eef5f8; }

.study-card {
  margin-top: 26px;
  padding: 18px 20px 20px;
  border: 1px solid rgb(238 241 239 / 80%);
  border-radius: 14px;
  background: #fff;
  box-shadow: var(--mock-card-shadow);
}

.study-card-head,
.study-target,
.quiz-progress-line,
.quiz-topbar,
.chapter-topbar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
}

.study-card-head button {
  border: 0;
  color: var(--mock-muted);
  background: transparent;
  font-size: 12px;
  font-weight: 800;
}

.study-stats {
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 10px;
  margin: 26px 0 22px;
  text-align: center;
}

.study-stats span,
.study-target {
  color: var(--mock-muted);
  font-size: 12px;
  font-weight: 760;
}

.study-stats strong {
  display: inline-block;
  margin-top: 8px;
  color: var(--mock-ink);
  font-size: 24px;
  font-weight: 920;
}

.study-stats small {
  margin-left: 3px;
  color: var(--mock-ink);
  font-size: 12px;
  font-weight: 800;
}

.study-target b {
  color: #676d69;
}

.study-progress {
  height: 5px;
  overflow: hidden;
  border-radius: 999px;
  background: #edf0ee;
}

.study-progress span {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--mock-green);
}

.chapter-topbar {
  min-height: 42px;
}

.chapter-back,
.quiz-back-button {
  display: grid;
  width: 34px;
  height: 34px;
  padding: 0;
  place-items: center;
  border: 0;
  color: #0f1513;
  background: transparent;
  font-size: 32px;
  line-height: 1;
}

.chapter-hero {
  position: relative;
  display: flex;
  align-items: center;
  justify-content: space-between;
  min-height: 142px;
  margin-bottom: 16px;
  padding: 20px 12px 20px 12px;
}

.chapter-hero h1 {
  color: var(--mock-ink);
  font-size: 28px;
  font-weight: 920;
}

.chapter-hero p {
  margin: 10px 0 0;
  color: #7e8580;
  font-size: 13px;
  font-weight: 780;
}

.chapter-note {
  display: grid;
  width: 98px;
  height: 98px;
  place-items: center;
  border-radius: 26px;
  color: #36bd8b;
  background: radial-gradient(circle at 50% 70%, rgb(28 142 106 / 28%), transparent 38%);
  filter: drop-shadow(0 18px 18px rgb(33 145 105 / 22%));
  font-size: 78px;
  font-weight: 900;
}

.chapter-list {
  display: grid;
  gap: 8px;
}

.chapter-row {
  display: grid;
  grid-template-columns: 64px minmax(0, 1fr) 126px 24px;
  align-items: center;
  gap: 10px;
  min-height: 74px;
  padding: 12px 14px;
  border: 1px solid rgb(238 241 239 / 88%);
  border-radius: 10px;
  background: #fff;
  box-shadow: 0 10px 26px rgb(15 30 26 / 6%);
  text-align: left;
}

.chapter-index,
.chapter-main strong,
.quiz-title-wrap strong,
.quiz-title-wrap span {
  color: var(--mock-ink);
  font-weight: 900;
}

.chapter-index {
  font-size: 12px;
}

.chapter-main {
  display: grid;
  min-width: 0;
  gap: 9px;
}

.chapter-main strong {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 14px;
}

.chapter-main small {
  color: #7e8580;
  font-size: 12px;
  font-weight: 760;
}

.chapter-line {
  height: 4px;
  overflow: hidden;
  border-radius: 999px;
  background: #e9ecea;
}

.chapter-line i {
  display: block;
  height: 100%;
  border-radius: inherit;
  background: var(--mock-green);
}

.chapter-lock,
.chapter-count {
  color: #8d918f;
  text-align: center;
  font-size: 16px;
}

.chapter-count {
  color: var(--mock-green);
  font-size: 11px;
  font-weight: 900;
}

.chapter-row.is-locked {
  cursor: default;
}

.chapter-test-mini {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  margin: 18px 0 4px;
  padding: 16px;
  border-radius: 14px;
  background: #fff;
  box-shadow: var(--mock-card-shadow);
}

.chapter-test-mini strong,
.chapter-test-mini span {
  display: block;
}

.chapter-test-mini strong {
  color: var(--mock-ink);
  font-size: 14px;
  font-weight: 900;
}

.chapter-test-mini span {
  margin-top: 6px;
  color: var(--mock-muted);
  font-size: 11px;
}

.chapter-test-mini button {
  min-width: 76px;
  height: 34px;
  border: 0;
  border-radius: 999px;
  color: #fff;
  background: var(--mock-green);
  font-size: 12px;
  font-weight: 900;
}

.quiz-page {
  padding: 10px 20px 18px;
}

.quiz-topbar {
  min-height: 48px;
  margin-bottom: 8px;
}

.quiz-title-wrap {
  flex: 1;
  display: flex;
  min-width: 0;
  gap: 16px;
  align-items: center;
}

.quiz-title-wrap strong,
.quiz-title-wrap span {
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 17px;
}

.quiz-top-actions {
  display: flex;
  gap: 14px;
}

.quiz-top-actions button {
  display: grid;
  min-width: 34px;
  padding: 0;
  border: 0;
  color: #0f1513;
  background: transparent;
  place-items: center;
  font-size: 20px;
}

.quiz-top-actions button span {
  margin-top: 2px;
  font-size: 10px;
  font-weight: 760;
}

.quiz-top-actions button.active {
  color: var(--mock-green);
}

.quiz-progress-line {
  margin: 4px 0 20px;
}

.quiz-progress-line .quiz-progress {
  flex: 1;
  height: 5px;
  margin: 0;
  background: #e8ecea;
}

.quiz-progress-line .quiz-progress span {
  background: var(--mock-green);
}

.quiz-progress-line b {
  color: var(--mock-ink);
  font-size: 13px;
  font-weight: 900;
}

.question-panel {
  padding: 0;
  border: 0;
  border-radius: 0;
  background: transparent;
  box-shadow: none;
}

.question-panel::before {
  display: none;
}

.question-meta {
  margin-bottom: 12px;
}

.meta-chip {
  padding: 7px 18px;
  border-radius: 999px;
  color: #202624;
  background: #e8e9e8;
  font-size: 12px;
  font-weight: 900;
}

.question-title {
  color: var(--mock-ink);
  font-size: 15px;
  line-height: 1.62;
  font-weight: 880;
}

.score-image {
  border-color: var(--mock-line);
  border-radius: 12px;
  box-shadow: none;
}

.options-list {
  gap: 10px;
  margin-top: 14px;
}

.option-button {
  grid-template-columns: 42px minmax(0, 1fr);
  min-height: 46px;
  padding: 8px 18px;
  border: 1px solid #e8ecea;
  border-radius: 10px;
  background: #fff;
  box-shadow: 0 5px 16px rgb(15 30 26 / 3%);
}

.option-key {
  width: 27px;
  height: 27px;
  border: 1px solid #dfe4e2;
  color: #343b38;
  background: #fff;
  font-size: 12px;
}

.option-copy {
  color: #171b19;
  font-size: 14px;
  font-weight: 800;
}

.option-button.selected {
  border-color: #f7d6d6;
  background: #fde2e2;
}

.option-button.selected .option-key {
  color: #fff;
  background: var(--mock-red);
}

.option-button.wrong {
  border-color: #ffd0d0;
  background: #ffdede;
}

.option-button.wrong .option-key {
  background: var(--mock-red);
}

.option-button.wrong .option-copy {
  color: var(--mock-red);
}

.option-button.correct {
  border-color: #cde9df;
  background: #eaf8f3;
}

.option-button.correct .option-key {
  background: var(--mock-green);
}

.answer-panel {
  margin-top: 14px;
  padding: 16px 18px;
  border: 0;
  border-radius: 12px;
  background: #fff;
  box-shadow: 0 10px 26px rgb(15 30 26 / 5%);
}

.answer-panel .answer-line {
  margin: 0 0 8px;
  font-size: 13px;
  font-weight: 900;
}

.answer-panel .answer-line.ok {
  color: var(--mock-green);
}

.answer-panel .answer-line.bad {
  color: var(--mock-red);
}

.answer-panel h2,
.video-lesson-card h2 {
  margin: 10px 0 8px;
  color: var(--mock-ink);
  font-size: 14px;
  font-weight: 900;
}

.answer-panel p:not(.answer-line) {
  margin: 0;
  color: #2f3633;
  font-size: 13px;
  line-height: 1.7;
  font-weight: 650;
}

.video-lesson-card {
  margin-top: 18px;
}

.video-entry {
  display: grid;
  grid-template-columns: 1fr;
  min-height: 178px;
  padding: 0;
  overflow: hidden;
  border: 0;
  border-radius: 10px;
  background: #071210;
  box-shadow: 0 12px 28px rgb(15 30 26 / 12%);
}

.video-preview {
  position: relative;
  display: grid;
  min-height: 178px;
  padding: 18px 20px;
  color: #fff;
  background:
    linear-gradient(90deg, rgb(5 18 16 / 96%), rgb(8 32 28 / 88%)),
    repeating-linear-gradient(90deg, rgb(255 255 255 / 88%) 0 13px, rgb(18 18 18 / 90%) 13px 20px);
  align-content: start;
}

.video-preview::after {
  position: absolute;
  right: 18px;
  bottom: 20px;
  width: 92px;
  height: 112px;
  border-radius: 42px 42px 8px 8px;
  background: linear-gradient(180deg, rgb(255 255 255 / 18%), rgb(255 255 255 / 4%));
  content: "";
}

.video-preview i {
  font-style: normal;
  font-size: 15px;
  font-weight: 900;
}

.video-preview b {
  position: absolute;
  top: 50%;
  left: 50%;
  display: grid;
  width: 48px;
  height: 48px;
  place-items: center;
  border-radius: 50%;
  color: #fff;
  background: rgb(0 0 0 / 34%);
  transform: translate(-50%, -50%);
}

.video-copy {
  display: none;
}

.quiz-actions {
  position: sticky;
  bottom: 0;
  display: grid;
  grid-template-columns: repeat(3, minmax(0, 1fr));
  gap: 14px;
  margin: 20px -2px 0;
  padding: 12px 0 0;
  background: linear-gradient(180deg, rgb(251 252 251 / 0%), #fbfcfb 24%);
}

.quiz-actions .secondary-command,
.quiz-actions .primary-command {
  min-height: 42px;
  border-radius: 999px;
  font-size: 14px;
  font-weight: 900;
}

.quiz-actions .secondary-command {
  border: 1px solid #e3e8e6;
  color: #202624;
  background: #fff;
  box-shadow: 0 5px 14px rgb(15 30 26 / 4%);
}

.quiz-actions .primary-command {
  border-color: var(--mock-green-dark);
  color: #fff;
  background: linear-gradient(180deg, #279b86, #0f6d5d);
  box-shadow: 0 8px 18px rgb(22 130 111 / 22%);
}

.quiz-hint {
  margin-top: 8px;
  color: var(--mock-muted);
}

.bottom-nav {
  border-top: 1px solid #edf0ee;
  background: #fff;
  box-shadow: 0 -8px 22px rgb(15 30 26 / 5%);
}

.nav-button {
  grid-template-rows: 25px 18px;
  color: #8f9692;
  font-weight: 760;
}

.nav-button .nav-icon {
  font-size: 22px;
}

.nav-button.active {
  color: var(--mock-green);
}

/* Gleb Kuznetsov inspired minimal tech pass: frosted gray, soft neon edge light, slow uniform motion. */
:root {
  --gk-bg: #eef0f2;
  --gk-bg-deep: #e4e7ea;
  --gk-ink: #171b20;
  --gk-muted: #727a83;
  --gk-line: rgb(255 255 255 / 58%);
  --gk-glass: rgb(255 255 255 / 48%);
  --gk-glass-strong: rgb(255 255 255 / 68%);
  --gk-shadow: 0 22px 56px rgb(64 76 92 / 14%);
  --gk-shadow-soft: 0 14px 34px rgb(64 76 92 / 10%);
  --gk-neon-a: #8fd7d2;
  --gk-neon-b: #b9b1e9;
  --gk-neon-c: #d7dfaa;
  --gk-ease: 520ms cubic-bezier(.25, .1, .25, 1);
}

body {
  background:
    linear-gradient(135deg, #f5f6f7 0%, #e9ecef 46%, #f3f4f1 100%);
}

body::before {
  position: fixed;
  inset: 0;
  z-index: -1;
  pointer-events: none;
  background:
    radial-gradient(ellipse at 22% 10%, rgb(143 215 210 / 20%), transparent 38%),
    radial-gradient(ellipse at 84% 18%, rgb(185 177 233 / 18%), transparent 42%),
    linear-gradient(180deg, rgb(255 255 255 / 42%), transparent 42%);
  content: "";
}

.device {
  background: linear-gradient(180deg, #f7f8f9, #dfe3e6);
  box-shadow:
    0 30px 82px rgb(57 69 85 / 22%),
    inset 0 1px 0 rgb(255 255 255 / 88%);
}

.device::before {
  border-color: rgb(255 255 255 / 52%);
}

.device-screen {
  background:
    radial-gradient(ellipse at 18% 0%, rgb(143 215 210 / 18%), transparent 34%),
    radial-gradient(ellipse at 100% 8%, rgb(185 177 233 / 16%), transparent 36%),
    linear-gradient(180deg, #f5f6f7 0%, #eaedf0 100%);
}

.system-bar {
  color: var(--gk-ink);
  background: linear-gradient(180deg, rgb(255 255 255 / 58%), rgb(255 255 255 / 18%));
  backdrop-filter: blur(18px);
}

.mobile-app,
.subjects-page,
.knowledge-page,
.quiz-page,
.profile-page {
  background: transparent;
}

.page {
  padding: 16px 18px 22px;
}

button,
input {
  transition:
    background-color var(--gk-ease),
    border-color var(--gk-ease),
    box-shadow var(--gk-ease),
    color var(--gk-ease),
    opacity var(--gk-ease),
    transform var(--gk-ease),
    filter var(--gk-ease);
}

button:focus-visible,
input:focus-visible {
  outline: 2px solid rgb(143 215 210 / 84%);
  outline-offset: 3px;
}

.home-greeting {
  margin: 10px 0 14px;
}

.home-greeting h1,
.section-heading h2,
.study-card h2,
.chapter-hero h1,
.question-title,
.quiz-title-wrap strong,
.quiz-title-wrap span {
  color: var(--gk-ink);
}

.home-greeting h1 {
  font-size: 22px;
  letter-spacing: 0;
}

.home-greeting h1 span {
  color: #548d8a;
  text-shadow: 0 0 18px rgb(143 215 210 / 48%);
}

.home-greeting p,
.chapter-hero p,
.study-stats span,
.study-target,
.subject-tile small,
.chapter-main small,
.quiz-hint {
  color: var(--gk-muted);
}

.checkin-button {
  color: var(--gk-ink);
  border-radius: 18px;
}

.checkin-button:hover {
  color: #4f8280;
  filter: drop-shadow(0 0 12px rgb(143 215 210 / 26%));
}

.frost-search {
  position: relative;
  z-index: 6;
  display: grid;
  grid-template-columns: 34px minmax(0, 1fr) 38px;
  align-items: center;
  min-height: 58px;
  margin: 0 0 16px;
  padding: 0 10px 0 14px;
  border: 1px solid rgb(255 255 255 / 62%);
  border-radius: 999px;
  background:
    linear-gradient(135deg, rgb(255 255 255 / 74%), rgb(255 255 255 / 38%)),
    linear-gradient(90deg, rgb(143 215 210 / 18%), rgb(185 177 233 / 14%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 78%),
    0 16px 42px rgb(76 88 104 / 12%),
    0 0 0 1px rgb(143 215 210 / 8%);
  backdrop-filter: blur(22px) saturate(1.15);
}

.frost-search::before {
  position: absolute;
  inset: -1px;
  z-index: -1;
  border-radius: inherit;
  background: linear-gradient(120deg, rgb(143 215 210 / 45%), transparent 28%, rgb(185 177 233 / 36%), transparent 74%, rgb(215 223 170 / 34%));
  opacity: 0.52;
  filter: blur(10px);
  content: "";
  transition: opacity var(--gk-ease), filter var(--gk-ease);
}

.frost-search:focus-within {
  transform: translateY(-1px);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 86%),
    0 22px 52px rgb(76 88 104 / 15%),
    0 0 0 1px rgb(143 215 210 / 28%);
}

.frost-search:focus-within::before {
  opacity: 0.82;
  filter: blur(13px);
}

.search-glyph {
  color: #6f7a84;
  font-size: 20px;
  line-height: 1;
}

.frost-search input {
  width: 100%;
  min-width: 0;
  border: 0;
  color: var(--gk-ink);
  background: transparent;
  font-size: 14px;
  font-weight: 720;
}

.frost-search input::placeholder {
  color: rgb(114 122 131 / 68%);
}

.frost-search input:focus {
  outline: 0;
}

.frost-search > button {
  display: grid;
  width: 34px;
  height: 34px;
  padding: 0;
  place-items: center;
  border: 1px solid rgb(255 255 255 / 62%);
  border-radius: 50%;
  color: #64717a;
  background: rgb(255 255 255 / 42%);
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 76%);
}

.frost-suggestions {
  position: absolute;
  top: calc(100% + 8px);
  right: 8px;
  left: 8px;
  z-index: 20;
  display: grid;
  gap: 6px;
  max-height: 210px;
  padding: 8px;
  overflow: auto;
  border: 1px solid rgb(255 255 255 / 64%);
  border-radius: 22px;
  background: rgb(248 249 250 / 74%);
  box-shadow: 0 22px 54px rgb(64 76 92 / 16%);
  backdrop-filter: blur(24px) saturate(1.12);
  opacity: 0;
  pointer-events: none;
  transform: translateY(8px);
  transition: opacity var(--gk-ease), transform var(--gk-ease);
}

.frost-search:focus-within .frost-suggestions {
  opacity: 1;
  pointer-events: auto;
  transform: translateY(0);
}

.frost-suggestions button {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  min-height: 38px;
  padding: 0 12px;
  border: 1px solid transparent;
  border-radius: 16px;
  color: var(--gk-ink);
  background: rgb(255 255 255 / 38%);
  font-size: 12px;
  font-weight: 780;
}

.frost-suggestions button:hover {
  border-color: rgb(143 215 210 / 32%);
  background: rgb(255 255 255 / 62%);
  transform: translateY(-1px);
}

.frost-suggestions small {
  overflow: hidden;
  color: var(--gk-muted);
  text-overflow: ellipsis;
  white-space: nowrap;
  font-size: 10px;
}

.practice-banner,
.study-card,
.subject-tile,
.chapter-row,
.chapter-test-mini,
.answer-panel,
.test-paper-strip,
.option-button,
.video-entry {
  border: 1px solid var(--gk-line);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 66%), rgb(255 255 255 / 34%));
  box-shadow: var(--gk-shadow-soft);
  backdrop-filter: blur(20px) saturate(1.08);
}

.practice-banner {
  min-height: 150px;
  margin-bottom: 20px;
  border-radius: 28px;
  color: var(--gk-ink);
  background:
    linear-gradient(135deg, rgb(252 253 254 / 68%), rgb(222 227 232 / 34%)),
    linear-gradient(120deg, rgb(143 215 210 / 14%), transparent 48%, rgb(185 177 233 / 13%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 72%),
    var(--gk-shadow),
    0 0 36px rgb(143 215 210 / 10%);
}

.practice-banner::before {
  position: absolute;
  inset: 0;
  border-radius: inherit;
  background:
    linear-gradient(120deg, rgb(143 215 210 / 34%), transparent 28%, rgb(185 177 233 / 28%), transparent 72%),
    linear-gradient(180deg, rgb(255 255 255 / 28%), transparent);
  opacity: 0.34;
  content: "";
}

.practice-banner h2,
.practice-banner p {
  color: var(--gk-ink);
}

.practice-banner h2 {
  font-size: 23px;
}

.practice-banner p {
  color: rgb(69 78 88 / 58%);
}

.piano-shine {
  opacity: 0.35;
  background:
    linear-gradient(158deg, transparent 0 22%, rgb(255 255 255 / 52%) 23% 30%, transparent 31% 100%),
    repeating-linear-gradient(105deg, rgb(88 96 106 / 9%) 0 8px, rgb(255 255 255 / 2%) 8px 16px);
}

.banner-dots span {
  background: rgb(87 96 106 / 24%);
}

.banner-dots span:first-child {
  background: var(--gk-neon-a);
  box-shadow: 0 0 14px rgb(143 215 210 / 54%);
}

.subject-tile-grid {
  gap: 12px;
}

.subject-tile {
  min-height: 126px;
  border-radius: 28px;
  box-shadow: var(--gk-shadow-soft);
  animation: gk-card-enter 620ms cubic-bezier(.25, .1, .25, 1) both;
}

.subject-tile:nth-child(2) { animation-delay: 55ms; }
.subject-tile:nth-child(3) { animation-delay: 110ms; }
.subject-tile:nth-child(4) { animation-delay: 165ms; }
.subject-tile:nth-child(5) { animation-delay: 220ms; }
.subject-tile:nth-child(6) { animation-delay: 275ms; }

.subject-tile:hover:not(.is-coming),
.chapter-row:hover,
.option-button:hover:not(.selected):not(.correct):not(.wrong),
.study-card:hover {
  transform: translateY(-2px);
  box-shadow:
    0 18px 44px rgb(64 76 92 / 13%),
    0 0 28px rgb(143 215 210 / 10%);
}

.subject-bubble {
  color: #53606a;
  background:
    linear-gradient(135deg, rgb(255 255 255 / 64%), rgb(255 255 255 / 28%)),
    radial-gradient(circle at 48% 40%, var(--tile-bg, rgb(143 215 210 / 26%)), transparent 58%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 76%),
    0 10px 22px rgb(64 76 92 / 10%);
  font-size: 25px;
}

.subject-tile strong,
.study-stats strong,
.chapter-main strong,
.chapter-test-mini strong {
  color: var(--gk-ink);
}

.study-card {
  border-radius: 30px;
}

.study-progress,
.chapter-line,
.quiz-progress-line .quiz-progress {
  background: rgb(111 122 132 / 12%);
}

.study-progress span,
.chapter-line i,
.quiz-progress-line .quiz-progress span {
  background: linear-gradient(90deg, var(--gk-neon-a), var(--gk-neon-b), var(--gk-neon-c));
  box-shadow: 0 0 18px rgb(143 215 210 / 28%);
}

.chapter-hero {
  min-height: 114px;
  padding: 16px 4px;
}

.chapter-note {
  color: #6fa9a4;
  background:
    linear-gradient(135deg, rgb(255 255 255 / 54%), rgb(255 255 255 / 18%)),
    radial-gradient(circle at 50% 72%, rgb(143 215 210 / 28%), transparent 58%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 72%),
    0 18px 42px rgb(90 115 120 / 14%);
  filter: none;
}

.chapter-search {
  margin-bottom: 14px;
}

.chapter-row {
  min-height: 76px;
  border-radius: 26px;
}

.chapter-lock,
.chapter-count {
  color: #6f7a84;
}

.chapter-test-mini {
  border-radius: 28px;
}

.chapter-test-mini button {
  color: #263035;
  background: linear-gradient(135deg, rgb(143 215 210 / 68%), rgb(215 223 170 / 56%));
  box-shadow: 0 10px 24px rgb(143 215 210 / 20%);
}

.quiz-page {
  padding-top: 12px;
}

.quiz-topbar {
  position: sticky;
  top: 0;
  z-index: 12;
  min-height: 58px;
  margin: -6px -8px 8px;
  padding: 0 8px;
  border-radius: 0 0 24px 24px;
  background: linear-gradient(180deg, rgb(245 246 247 / 88%), rgb(245 246 247 / 54%));
  backdrop-filter: blur(18px);
}

.quiz-back-button,
.chapter-back,
.quiz-top-actions button {
  color: #505a64;
}

.quiz-top-actions button {
  border-radius: 16px;
}

.quiz-top-actions button:hover,
.quiz-back-button:hover,
.chapter-back:hover {
  color: #4f8682;
  background: rgb(255 255 255 / 34%);
}

.question-panel {
  padding: 16px 16px 18px;
  border: 1px solid var(--gk-line);
  border-radius: 28px;
  background: linear-gradient(135deg, rgb(255 255 255 / 58%), rgb(255 255 255 / 30%));
  box-shadow: var(--gk-shadow-soft);
  backdrop-filter: blur(18px);
}

.question-meta {
  margin-bottom: 10px;
}

.meta-chip {
  color: #535e68;
  background: rgb(255 255 255 / 46%);
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 68%);
}

.option-button {
  min-height: 52px;
  border-radius: 22px;
}

.option-key {
  border-color: rgb(255 255 255 / 62%);
  color: #58636c;
  background: rgb(255 255 255 / 46%);
}

.option-button.selected,
.option-button.wrong {
  border-color: rgb(239 101 101 / 24%);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 56%), rgb(255 226 226 / 42%));
  box-shadow: 0 12px 30px rgb(239 75 75 / 10%);
}

.option-button.correct {
  border-color: rgb(143 215 210 / 34%);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 60%), rgb(223 250 246 / 42%));
  box-shadow: 0 12px 30px rgb(143 215 210 / 12%);
}

.answer-panel {
  border-radius: 28px;
}

.video-entry {
  border-radius: 28px;
  background:
    linear-gradient(135deg, rgb(33 42 49 / 92%), rgb(52 58 69 / 82%)),
    linear-gradient(120deg, rgb(143 215 210 / 18%), rgb(185 177 233 / 14%));
}

.video-preview {
  background:
    linear-gradient(120deg, rgb(19 29 35 / 92%), rgb(39 45 55 / 76%)),
    linear-gradient(90deg, rgb(143 215 210 / 12%), transparent, rgb(185 177 233 / 12%));
}

.video-preview b {
  background: rgb(255 255 255 / 16%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 48%),
    0 0 28px rgb(143 215 210 / 18%);
  backdrop-filter: blur(14px);
}

.quiz-actions {
  background: linear-gradient(180deg, rgb(238 240 242 / 0%), rgb(238 240 242 / 88%) 28%);
}

.quiz-actions .secondary-command,
.quiz-actions .primary-command {
  min-height: 44px;
  border-radius: 999px;
}

.quiz-actions .secondary-command {
  border-color: rgb(255 255 255 / 62%);
  background: rgb(255 255 255 / 46%);
  box-shadow: inset 0 1px 0 rgb(255 255 255 / 72%), 0 10px 24px rgb(64 76 92 / 9%);
}

.quiz-actions .primary-command {
  border-color: rgb(143 215 210 / 32%);
  color: #263035;
  background: linear-gradient(135deg, rgb(143 215 210 / 72%), rgb(215 223 170 / 56%));
  box-shadow: 0 14px 30px rgb(143 215 210 / 22%);
}

.bottom-nav {
  border-top-color: rgb(255 255 255 / 58%);
  background: rgb(247 248 249 / 64%);
  box-shadow: 0 -16px 42px rgb(64 76 92 / 12%);
  backdrop-filter: blur(22px) saturate(1.08);
}

.nav-button {
  color: #78818a;
}

.nav-button.active {
  color: #4f8682;
  text-shadow: 0 0 16px rgb(143 215 210 / 36%);
}

.app-toast {
  color: #263035;
  background: rgb(255 255 255 / 72%);
  box-shadow: 0 18px 42px rgb(64 76 92 / 16%);
  backdrop-filter: blur(18px);
}

@keyframes gk-card-enter {
  from {
    opacity: 0;
    transform: translateY(10px);
  }
}

@media (prefers-reduced-motion: reduce) {
  .subject-tile {
    animation: none;
  }
}

/* Richer sci-fi color pass: still frosted and restrained, with more spectral accents. */
:root {
  --sci-cyan: #7de5ea;
  --sci-blue: #83a7ff;
  --sci-violet: #b691ff;
  --sci-pink: #eda7d7;
  --sci-lime: #d4eba7;
  --sci-amber: #f0cf8d;
  --sci-ink: #151922;
  --sci-muted: #6f7784;
  --sci-glass: rgb(255 255 255 / 50%);
  --sci-border: rgb(255 255 255 / 66%);
}

body {
  background:
    radial-gradient(ellipse at 9% 14%, rgb(125 229 234 / 24%), transparent 34%),
    radial-gradient(ellipse at 90% 8%, rgb(182 145 255 / 22%), transparent 36%),
    radial-gradient(ellipse at 78% 92%, rgb(237 167 215 / 18%), transparent 40%),
    linear-gradient(135deg, #f3f5f8 0%, #e8ebf0 46%, #f5f2f6 100%);
}

.device-screen {
  background:
    radial-gradient(ellipse at 8% 4%, rgb(125 229 234 / 22%), transparent 35%),
    radial-gradient(ellipse at 92% 10%, rgb(182 145 255 / 20%), transparent 38%),
    radial-gradient(ellipse at 42% 102%, rgb(212 235 167 / 18%), transparent 38%),
    linear-gradient(180deg, #f7f8fb 0%, #eceff4 100%);
}

.frost-search {
  background:
    linear-gradient(135deg, rgb(255 255 255 / 76%), rgb(255 255 255 / 38%)),
    linear-gradient(98deg, rgb(125 229 234 / 20%), rgb(131 167 255 / 15%) 36%, rgb(182 145 255 / 16%) 64%, rgb(237 167 215 / 13%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 82%),
    0 18px 46px rgb(73 83 105 / 14%),
    0 0 0 1px rgb(125 229 234 / 10%),
    0 0 34px rgb(182 145 255 / 8%);
}

.frost-search::before {
  background: linear-gradient(115deg, var(--sci-cyan), transparent 22%, var(--sci-blue) 38%, var(--sci-violet) 55%, transparent 72%, var(--sci-pink));
  opacity: 0.56;
}

.frost-search:focus-within {
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 88%),
    0 24px 58px rgb(73 83 105 / 16%),
    0 0 0 1px rgb(125 229 234 / 30%),
    0 0 44px rgb(182 145 255 / 12%);
}

.practice-banner {
  color: var(--sci-ink);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 70%), rgb(236 240 247 / 42%)),
    linear-gradient(120deg, rgb(125 229 234 / 18%), transparent 32%, rgb(131 167 255 / 15%) 48%, rgb(182 145 255 / 14%) 66%, rgb(237 167 215 / 13%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 76%),
    0 24px 58px rgb(73 83 105 / 16%),
    0 0 48px rgb(125 229 234 / 10%);
}

.practice-banner::before {
  background:
    linear-gradient(112deg, rgb(125 229 234 / 36%), transparent 22%, rgb(131 167 255 / 28%) 38%, rgb(182 145 255 / 26%) 58%, transparent 74%, rgb(237 167 215 / 28%)),
    repeating-linear-gradient(90deg, transparent 0 22px, rgb(255 255 255 / 16%) 23px, transparent 24px 46px);
}

.piano-shine {
  opacity: 0.48;
  background:
    linear-gradient(158deg, transparent 0 20%, rgb(255 255 255 / 66%) 22% 29%, transparent 31% 100%),
    repeating-linear-gradient(105deg, rgb(75 88 115 / 10%) 0 8px, rgb(125 229 234 / 5%) 8px 16px);
}

.banner-dots span:first-child {
  background: var(--sci-cyan);
  box-shadow: 0 0 16px rgb(125 229 234 / 62%);
}

.banner-dots span:nth-child(2) {
  background: rgb(131 167 255 / 54%);
}

.banner-dots span:nth-child(3) {
  background: rgb(182 145 255 / 48%);
}

.subject-tile,
.study-card,
.chapter-row,
.chapter-test-mini,
.question-panel,
.answer-panel,
.option-button {
  border-color: var(--sci-border);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 66%), rgb(255 255 255 / 34%)),
    linear-gradient(130deg, rgb(125 229 234 / 6%), rgb(182 145 255 / 5%) 56%, rgb(237 167 215 / 5%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 74%),
    0 16px 40px rgb(73 83 105 / 11%);
}

.subject-tile:hover:not(.is-coming),
.chapter-row:hover,
.option-button:hover:not(.selected):not(.correct):not(.wrong),
.study-card:hover {
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 82%),
    0 20px 48px rgb(73 83 105 / 14%),
    0 0 30px rgb(125 229 234 / 12%),
    0 0 42px rgb(182 145 255 / 8%);
}

.subject-tile.tone-green { --tile-bg: rgb(125 229 234 / 32%); }
.subject-tile.tone-violet { --tile-bg: rgb(182 145 255 / 32%); }
.subject-tile.tone-orange { --tile-bg: rgb(240 207 141 / 34%); }
.subject-tile.tone-blue { --tile-bg: rgb(131 167 255 / 32%); }
.subject-tile.tone-amber { --tile-bg: rgb(212 235 167 / 32%); }
.subject-tile.tone-navy { --tile-bg: rgb(237 167 215 / 24%); }

.subject-bubble {
  color: #47525f;
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 80%),
    0 12px 26px rgb(73 83 105 / 11%),
    0 0 24px var(--tile-bg, rgb(125 229 234 / 18%));
}

.home-greeting h1 span,
.chapter-note {
  color: #558fb2;
  text-shadow:
    0 0 16px rgb(125 229 234 / 42%),
    0 0 30px rgb(182 145 255 / 16%);
}

.chapter-note {
  background:
    linear-gradient(135deg, rgb(255 255 255 / 58%), rgb(255 255 255 / 20%)),
    radial-gradient(circle at 35% 32%, rgb(125 229 234 / 34%), transparent 50%),
    radial-gradient(circle at 70% 72%, rgb(182 145 255 / 26%), transparent 55%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 78%),
    0 20px 48px rgb(73 83 105 / 14%),
    0 0 38px rgb(125 229 234 / 12%);
}

.study-progress span,
.chapter-line i,
.quiz-progress-line .quiz-progress span {
  background: linear-gradient(90deg, var(--sci-cyan), var(--sci-blue), var(--sci-violet), var(--sci-pink), var(--sci-lime));
  background-size: 220% 100%;
  box-shadow:
    0 0 18px rgb(125 229 234 / 30%),
    0 0 28px rgb(182 145 255 / 16%);
  animation: sci-spectrum-flow 7s linear infinite;
}

.chapter-test-mini button,
.quiz-actions .primary-command {
  color: #202833;
  background: linear-gradient(135deg, rgb(125 229 234 / 78%), rgb(131 167 255 / 56%) 48%, rgb(212 235 167 / 58%));
  box-shadow:
    0 14px 30px rgb(125 229 234 / 22%),
    0 0 30px rgb(182 145 255 / 10%);
}

.meta-chip {
  color: #505c6d;
  background:
    linear-gradient(135deg, rgb(255 255 255 / 58%), rgb(255 255 255 / 30%)),
    linear-gradient(90deg, rgb(125 229 234 / 12%), rgb(182 145 255 / 10%));
}

.option-button.correct {
  border-color: rgb(125 229 234 / 42%);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 62%), rgb(221 250 252 / 46%)),
    linear-gradient(90deg, rgb(125 229 234 / 16%), rgb(212 235 167 / 14%));
}

.option-button.selected,
.option-button.wrong {
  border-color: rgb(237 167 215 / 40%);
  background:
    linear-gradient(135deg, rgb(255 255 255 / 60%), rgb(255 226 241 / 42%)),
    linear-gradient(90deg, rgb(237 167 215 / 16%), rgb(182 145 255 / 12%));
}

.video-entry {
  background:
    linear-gradient(135deg, rgb(26 34 48 / 94%), rgb(47 55 78 / 86%)),
    linear-gradient(120deg, rgb(125 229 234 / 22%), rgb(131 167 255 / 16%) 42%, rgb(182 145 255 / 18%) 72%);
  box-shadow:
    0 18px 42px rgb(44 56 80 / 18%),
    0 0 36px rgb(125 229 234 / 12%);
}

.video-preview {
  background:
    linear-gradient(120deg, rgb(18 28 42 / 94%), rgb(41 47 69 / 78%)),
    linear-gradient(90deg, rgb(125 229 234 / 16%), transparent 42%, rgb(182 145 255 / 18%));
}

.bottom-nav {
  background:
    linear-gradient(135deg, rgb(255 255 255 / 70%), rgb(244 246 249 / 46%)),
    linear-gradient(90deg, rgb(125 229 234 / 9%), rgb(182 145 255 / 8%));
}

.nav-button.active {
  color: #527bd6;
  text-shadow:
    0 0 14px rgb(125 229 234 / 34%),
    0 0 24px rgb(182 145 255 / 22%);
}

@keyframes sci-spectrum-flow {
  from { background-position: 0% 50%; }
  to { background-position: 220% 50%; }
}

@media (prefers-reduced-motion: reduce) {
  .study-progress span,
  .chapter-line i,
  .quiz-progress-line .quiz-progress span {
    animation: none;
  }
}

/* QUESTION_PICKER_START: isolated preview-only question picker; safe to remove. */
.question-picker-section {
  color: #172033;
}

.question-picker-section h2 {
  margin: 0 0 14px;
  color: #172033;
  font-size: 30px;
  font-weight: 900;
  line-height: 1.18;
}

.picker-copy {
  margin: 0 0 22px;
  color: #69758b;
  font-size: 17px;
  font-weight: 720;
  line-height: 1.75;
}

.question-picker-select,
.question-picker-input {
  width: 100%;
  min-height: 56px;
  margin-bottom: 12px;
  padding: 0 18px;
  border: 1px solid #d7e0eb;
  border-radius: 14px;
  color: #172033;
  background:
    linear-gradient(135deg, rgb(255 255 255 / 76%), rgb(255 255 255 / 42%)),
    linear-gradient(120deg, rgb(125 229 234 / 8%), rgb(182 145 255 / 7%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 78%),
    0 10px 28px rgb(70 86 110 / 8%);
  backdrop-filter: blur(18px);
  font-size: 21px;
  font-weight: 840;
}

.question-picker-input::placeholder {
  color: #8b929c;
}

.question-picker-filters {
  display: flex;
  flex-wrap: wrap;
  gap: 10px 14px;
  margin: 12px 0 18px;
}

.question-picker-filters button {
  min-height: 52px;
  padding: 0 22px;
  border: 1px solid #d7e0eb;
  border-radius: 14px;
  color: #34415a;
  background: rgb(255 255 255 / 54%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 76%),
    0 8px 22px rgb(70 86 110 / 7%);
  font-size: 19px;
  font-weight: 850;
}

.question-picker-filters button:hover {
  transform: translateY(-1px);
  border-color: rgb(125 229 234 / 58%);
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 82%),
    0 14px 30px rgb(70 86 110 / 10%),
    0 0 24px rgb(125 229 234 / 12%);
}

.question-picker-filters button.active {
  color: #fff;
  border-color: #172033;
  background:
    linear-gradient(135deg, #172033, #0f1626),
    linear-gradient(90deg, rgb(125 229 234 / 24%), rgb(182 145 255 / 22%));
  box-shadow:
    0 14px 30px rgb(23 32 51 / 20%),
    0 0 24px rgb(125 229 234 / 12%);
}

.question-picker-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(66px, 1fr));
  gap: 12px 14px;
  max-height: 620px;
  overflow: auto;
  padding: 2px 2px 12px;
  scrollbar-width: thin;
}

.question-picker-grid button {
  position: relative;
  display: grid;
  min-width: 0;
  min-height: 62px;
  place-items: center;
  border: 1px solid #d7e0eb;
  border-radius: 14px;
  color: #172033;
  background:
    linear-gradient(135deg, rgb(255 255 255 / 70%), rgb(255 255 255 / 38%));
  box-shadow:
    inset 0 1px 0 rgb(255 255 255 / 76%),
    0 8px 20px rgb(70 86 110 / 7%);
  font-size: 20px;
  font-weight: 900;
}

.question-picker-grid button.has-image::after {
  position: absolute;
  top: 10px;
  right: 10px;
  width: 8px;
  height: 8px;
  border-radius: 50%;
  background: #f59b12;
  box-shadow: 0 0 10px rgb(245 155 18 / 38%);
  content: "";
}

.question-picker-grid button.is-candidate {
  border-color: rgb(240 207 141 / 72%);
  background:
    linear-gradient(135deg, rgb(255 248 222 / 76%), rgb(255 255 255 / 42%));
}

.question-picker-grid button.active {
  color: #fff;
  border-color: #3368f0;
  background:
    linear-gradient(135deg, #3368f0, #7658f2),
    linear-gradient(90deg, rgb(125 229 234 / 18%), rgb(237 167 215 / 18%));
  box-shadow:
    0 14px 32px rgb(51 104 240 / 24%),
    0 0 28px rgb(125 229 234 / 14%);
}

.question-picker-grid button.active.has-image::after {
  background: #ffd15d;
}

@media (max-width: 900px) {
  .question-picker-section h2 {
    font-size: 24px;
  }

  .picker-copy,
  .question-picker-filters button {
    font-size: 15px;
  }

  .question-picker-select,
  .question-picker-input {
    font-size: 17px;
  }
}
/* QUESTION_PICKER_END */

@keyframes quiz-slide-out-left {
  from { opacity: 0; transform: translateX(30px); }
  to { opacity: 1; transform: translateX(0); }
}

@keyframes quiz-slide-in-right {
  from { opacity: 0; transform: translateX(-30px); }
  to { opacity: 1; transform: translateX(0); }
}

.quiz-page.quiz-transition-next { animation: quiz-slide-out-left .28s ease-out both; }
.quiz-page.quiz-transition-previous { animation: quiz-slide-in-right .28s ease-out both; }

.vip-blur-gate { position: relative; margin: 18px 16px; overflow: hidden; border-radius: 22px; background: #f2f5ea; min-height: 310px; }
.vip-blur-question { padding: 26px 22px; filter: blur(9px); opacity: .72; user-select: none; }
.vip-blur-question h2 { margin: 0 0 24px; color: #384133; font-size: 21px; line-height: 1.6; }
.vip-blur-options div { margin: 12px 0; padding: 13px 15px; border: 1px solid rgba(87, 105, 70, .25); border-radius: 12px; color: #53624a; }
.vip-blur-options b { margin-right: 10px; }
.vip-blur-overlay { position: absolute; inset: 0; display: flex; flex-direction: column; align-items: center; justify-content: center; gap: 14px; padding: 24px; text-align: center; background: rgba(239, 245, 232, .56); }
.vip-blur-overlay strong { color: #263021; font-size: 20px; font-weight: 500; }
.vip-lock-icon { color: #b58a32; font-size: 34px; }
.vip-blur-overlay button { min-width: 210px; padding: 13px 24px; border: 2px solid #58733f; border-radius: 999px; background: #789d56; color: #fff; font-size: 16px; font-weight: 700; box-shadow: 0 3px 0 #536d3e; }
.vip-unlock-modal-backdrop { position: absolute; inset: 0; z-index: 30; display: grid; place-items: center; padding: 22px; background: rgba(39, 31, 24, .48); }
.vip-unlock-modal { position: relative; width: min(100%, 340px); padding: 28px 22px 20px; border-radius: 24px; text-align: center; background: #fffaf0; box-shadow: 0 18px 50px rgba(40, 27, 13, .25); }
.vip-unlock-close { position: absolute; top: 10px; right: 14px; border: 0; background: transparent; color: #8d7b68; font-size: 24px; }
.vip-unlock-crown, .vip-crown { color: #ae8645; font-size: 30px; }
.vip-unlock-modal h2 { margin: 8px 0; color: #493a2c; }
.vip-unlock-modal p { margin: 0 0 18px; color: #806f5d; font-size: 14px; line-height: 1.7; }
.vip-unlock-primary, .vip-buy-button { width: 100%; padding: 12px; border: 0; border-radius: 999px; background: #9a7742; color: #fffaf0; font-weight: 700; }
.vip-unlock-secondary { margin-top: 10px; border: 0; background: transparent; color: #8d7b68; }
.vip-page { padding: 20px; }
.vip-hero { padding: 18px; border-radius: 24px; text-align: center; background: linear-gradient(145deg, #f5e6c4, #fff9ed); }
.vip-hero .chapter-back { display: block; }
.vip-hero h1 { margin: 8px 0 4px; color: #493a2c; }
.vip-hero p, .vip-note { color: #806f5d; font-size: 13px; }
.vip-benefit-list { margin: 18px 0; padding: 4px 16px; border-radius: 18px; background: #fffaf0; }
.vip-benefit-list div { padding: 14px 0; border-bottom: 1px solid rgba(100, 75, 45, .12); }
.vip-benefit-list div:last-child { border-bottom: 0; }
.vip-benefit-list strong, .vip-benefit-list span { display: block; }
.vip-benefit-list span { margin-top: 4px; color: #8d7b68; font-size: 12px; }
.vip-note { text-align: center; }

@media (prefers-reduced-motion: reduce) {
  .quiz-page.quiz-transition-next,
  .quiz-page.quiz-transition-previous { animation: none; }
}

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.course-tile-grid{display:grid;grid-template-columns:1fr;gap:14px}.course-tile{min-height:126px;border:1px solid #e4ecea;border-radius:24px;padding:18px 18px;display:flex;flex-direction:column;align-items:flex-start;text-align:left;position:relative;background:#fff;box-shadow:0 8px 22px #173f3710}.course-tile-icon{display:grid;place-items:center;width:50px;height:50px;border-radius:17px;background:#fff;color:#168c73;font-size:28px;box-shadow:0 5px 14px #173f3714;margin-bottom:12px}.course-tile-copy{display:grid;gap:5px}.course-tile-copy strong{font-size:17px;color:#173b36}.course-tile-copy small{font-size:12px;color:#79908c}.course-tile-copy em{font-style:normal;font-size:11px;color:#159275}.course-tile .course-arrow{position:absolute;right:18px;top:18px;font-size:24px}.course-tile.tone-green{background:linear-gradient(145deg,#e5f7f0,#fff)}.course-tile.tone-blue{background:linear-gradient(145deg,#eaf1ff,#fff)}.course-tile.tone-orange{background:linear-gradient(145deg,#fff1df,#fff)}.course-tile.tone-navy{background:linear-gradient(145deg,#eef4f8,#fff)}.course-tile.tone-violet{background:linear-gradient(145deg,#f1ecff,#fff)}
.course-tile{border-color:rgb(255 255 255 / 72%);background:rgb(255 255 255 / 42%);backdrop-filter:blur(18px) saturate(135%);-webkit-backdrop-filter:blur(18px) saturate(135%);box-shadow:inset 0 1px 0 rgb(255 255 255 / 82%),0 10px 26px rgb(31 73 68 / 12%)}.course-tile-icon{background:rgb(255 255 255 / 58%);box-shadow:inset 0 1px 0 rgb(255 255 255 / 85%),0 5px 14px rgb(23 63 55 / 10%)}.course-tile.tone-green{background:linear-gradient(145deg,rgb(184 239 222 / 52%),rgb(255 255 255 / 38%))}.course-tile.tone-blue{background:linear-gradient(145deg,rgb(190 214 255 / 52%),rgb(255 255 255 / 38%))}.course-tile.tone-orange{background:linear-gradient(145deg,rgb(255 220 176 / 54%),rgb(255 255 255 / 38%))}.course-tile.tone-navy{background:linear-gradient(145deg,rgb(203 224 237 / 54%),rgb(255 255 255 / 38%))}.course-tile.tone-violet{background:linear-gradient(145deg,rgb(222 208 255 / 54%),rgb(255 255 255 / 38%))}
.course-tile{overflow:hidden;isolation:isolate;transition:transform .22s ease,box-shadow .22s ease}.course-tile::before{content:"";position:absolute;inset:-60% 25% 45% -25%;background:linear-gradient(120deg,rgb(255 255 255 / 58%),transparent 60%);transform:rotate(-8deg);pointer-events:none;z-index:-1}.course-tile:hover{transform:translateY(-3px);box-shadow:inset 0 1px 0 rgb(255 255 255 / 90%),0 16px 32px rgb(31 73 68 / 18%)}
.course-access{position:absolute;right:52px;top:21px;border-radius:999px;padding:4px 8px;font-size:11px;font-style:normal}.course-access.owned{color:#087a59;background:#d9f7e9}.course-access.locked{color:#8a6a2b;background:#fff0cf}.course-purchase-card,.course-admin-card{display:grid;gap:8px;margin:0 0 16px;padding:18px;border:1px solid #f0dfb5;border-radius:20px;background:linear-gradient(135deg,#fff9eb,#fff);box-shadow:0 8px 20px #82642a10}.course-purchase-card strong,.course-admin-card strong{color:#5d4924;font-size:17px}.course-purchase-card span,.course-admin-card span,.course-purchase-card small{color:#927b4d;font-size:13px;line-height:1.5}.course-purchase-card button,.course-admin-card button{border:0;border-radius:12px;padding:12px;background:linear-gradient(135deg,#e8aa38,#c98017);color:#fff;font-size:15px;font-weight:700}.course-admin-card{border-color:#d4ddee;background:#f6f9ff}.course-admin-card button{background:#4e83d7}.course-lesson-locked{opacity:.7;background:#f8f8f7}.lesson-access{display:grid;place-items:center;min-width:28px;color:#63958a;font-size:17px}
.profile-admin-entry{width:100%;margin-top:18px;padding:13px;border:1px solid #cfe4dc;border-radius:14px;background:#f5fffa;color:#287865;font-weight:700}.purchase-contact-backdrop{position:absolute;inset:0;z-index:40;display:grid;place-items:center;padding:22px;background:rgb(30 44 38 / 52%)}.purchase-contact-modal{position:relative;width:min(100%,340px);padding:28px 23px 22px;border-radius:24px;background:#fffdf8;text-align:center;box-shadow:0 18px 48px #17302555}.purchase-contact-close{position:absolute;right:14px;top:12px;border:0;background:transparent;color:#8b8171;font-size:28px}.purchase-contact-icon{display:grid;place-items:center;width:50px;height:50px;margin:0 auto 10px;border-radius:17px;background:#ddf7eb;color:#16845e;font-size:25px}.purchase-contact-modal h2{margin:0 0 9px;color:#3f382d}.purchase-contact-modal p{margin:0;color:#817565;font-size:14px;line-height:1.65}.purchase-account{display:grid;gap:4px;margin:17px 0;padding:12px;border-radius:13px;background:#f5f2e9;text-align:left}.purchase-account span{font-size:12px;color:#9a8b74}.purchase-account strong{color:#5b513f;font-size:13px;word-break:break-all}.purchase-contact-confirm,.course-video-buy{width:100%;border:0;border-radius:13px;padding:13px;background:linear-gradient(135deg,#e8aa38,#c98017);color:#fff;font-size:15px;font-weight:700}.course-playback-page{padding-top:22px}.course-video-stage{min-height:215px;display:grid;align-content:center;justify-items:center;gap:11px;border-radius:23px;background:radial-gradient(circle at 70% 15%,#94dcc7,#173e3c 60%,#102928);color:#fff;box-shadow:0 12px 28px #173e3c35}.course-video-play{display:grid;place-items:center;width:56px;height:56px;border-radius:50%;padding-left:3px;background:#ffffff2d;border:1px solid #ffffff65;font-size:22px}.course-video-stage small{color:#d5eee8}.course-video-info{margin:19px 0}.course-video-info span{color:#299676;font-size:13px}.course-video-info h1{margin:6px 0;font-size:22px;color:#213e38}.course-video-info p{margin:0;color:#788b85;font-size:14px;line-height:1.6}.course-admin-page{padding-top:22px}.course-admin-heading{padding:18px;border-radius:20px;background:linear-gradient(135deg,#eaf3ff,#f7fbff)}.course-admin-heading span{color:#4d7fc9;font-size:13px;font-weight:700}.course-admin-heading h1{margin:5px 0;color:#274470;font-size:24px}.course-admin-heading p,.course-admin-note p{margin:0;color:#7487a2;font-size:13px;line-height:1.6}.course-admin-form{display:grid;gap:15px;margin:18px 0}.course-admin-form label{display:grid;gap:7px;color:#425673;font-size:14px;font-weight:700}.course-admin-form input,.course-admin-form select{width:100%;box-sizing:border-box;padding:13px;border:1px solid #dbe4f0;border-radius:12px;background:#fff;color:#30425e;font-size:15px}.course-admin-form button{border:0;border-radius:13px;padding:14px;background:#4e83d7;color:#fff;font-weight:700;font-size:16px}.course-admin-note{padding:15px;border-radius:16px;background:#f7f8fa}.course-admin-note strong{color:#526177;font-size:14px}
.purchase-qr-modal{padding-top:30px}.purchase-qr-modal p{margin-bottom:12px}.purchase-wechat-qr{display:block;width:min(100%,254px);margin:0 auto 10px;border-radius:8px}.purchase-qr-modal small{display:block;margin:0 0 15px;color:#938574;font-size:12px}
.chapter-editor{display:grid;grid-template-columns:1fr auto auto;gap:8px;align-items:center;margin:12px 0;padding:12px;border:1px solid #b8dfd4;border-radius:16px;background:#effaf6}.chapter-editor div{display:grid;gap:3px}.chapter-editor small{color:#6e8983;font-size:11px}.chapter-editor select{grid-column:1 / -1;padding:9px;border:1px solid #c8e3db;border-radius:10px;background:#fff;color:#24433d}.chapter-editor button{border:0;border-radius:9px;padding:8px 12px;background:#198f73;color:#fff}.chapter-editor button:last-child{background:#5078d8}
.chapter-concept-check{grid-column:1 / -1;display:flex;align-items:center;gap:7px;font-size:12px;color:#315850}.chapter-concept-check input{accent-color:#198f73}
.login-page{min-height:100%;display:flex;flex-direction:column;align-items:center;justify-content:center;padding:36px 28px;text-align:center;background:radial-gradient(circle at 50% 20%,#e1fbef,#f8fbff 58%,#fff)}.login-mark{display:grid;place-items:center;width:78px;height:78px;border-radius:28px;margin-bottom:22px;background:linear-gradient(145deg,#2fcb91,#128868);color:#fff;font-size:42px;box-shadow:0 16px 30px #168a6940}.login-page h1{margin:0;color:#183d37;font-size:25px}.login-page p{margin:10px 0 32px;color:#718783}.wechat-login-button{display:flex;justify-content:center;align-items:center;gap:10px;width:100%;border:0;border-radius:15px;padding:15px;background:#08bb50;color:#fff;font-size:17px;font-weight:700;box-shadow:0 10px 22px #08a64835}.wechat-login-button span{font-size:20px}.login-page small{margin-top:16px;color:#91a29f;line-height:1.6}