:root {
  color-scheme: light dark;
  --bg-a: #f8f0df;
  --bg-b: #eef4e8;
  --bg-c: #e6efe9;
  --surface: #fff;
  --surface-strong: #fff;
  --text: #1e2732;
  --muted: #5b6675;
  --accent: #166b4a;
  --accent-2: #b8892a;
  --line: rgba(30, 39, 50, 0.08);
  --shadow: 0 18px 44px rgba(34, 44, 55, 0.13);
  --radius-xl: 32px;
  --reader-scale: 1.08;
}

@media (prefers-color-scheme: dark) {
  :root {
    --bg-a: #14181f;
    --bg-b: #171d24;
    --bg-c: #1a2229;
    --surface: #222a33;
    --surface-strong: #1c232c;
    --text: #eef2f6;
    --muted: #9aa6b4;
    --line: rgba(255, 255, 255, 0.1);
    --shadow: 0 18px 44px rgba(0, 0, 0, 0.35);
  }
}

* {
  box-sizing: border-box;
}

button {
  font-size: 16px;
  -webkit-text-size-adjust: 100%;
  text-size-adjust: 100%;
}

html {
  scroll-behavior: smooth;
  -webkit-tap-highlight-color: transparent;
  font-size: 16px;
}

body {
  margin: 0;
  min-height: 100vh;
  overflow-x: hidden;
  color: var(--text);
  background: linear-gradient(180deg, var(--bg-a), var(--bg-b) 50%, var(--bg-c));
  font-family: "PingFang SC", "Hiragino Sans GB", "Source Han Sans SC", "Microsoft YaHei", system-ui, sans-serif;
}

.app-shell {
  width: min(100%, 920px);
  margin: 0 auto;
  padding: 16px 16px calc(92px + env(safe-area-inset-bottom));
  display: flex;
  flex-direction: column;
}

.top-hero {
  padding: 18px 18px 16px;
  border-radius: 24px;
  background: color-mix(in srgb, var(--surface) 78%, transparent);
  border: 1px solid color-mix(in srgb, var(--surface) 70%, transparent);
  box-shadow: var(--shadow);
}

.hero-row {
  display: flex;
  align-items: center;
  gap: 10px;
  flex-wrap: wrap;
}

.back-link {
  color: var(--accent);
  text-decoration: none;
  font-weight: 800;
  font-size: 0.95rem;
}

.pill {
  display: inline-flex;
  align-items: center;
  padding: 6px 12px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  color: var(--accent);
  font-size: 0.82rem;
  font-weight: 800;
  letter-spacing: 0.04em;
}

h1,
h2,
p {
  margin: 0;
}

h1 {
  margin-top: 12px;
  font-size: clamp(1.45rem, 5vw, 2.4rem);
  line-height: 1.15;
  font-weight: 800;
  font-family: "Songti SC", "STSong", "Noto Serif SC", Georgia, serif;
}

.disclaimer {
  margin-top: 8px;
  color: var(--muted);
  font-size: 0.9rem;
  line-height: 1.55;
}

.reader {
  margin-top: 14px;
  padding: 16px;
  border-radius: var(--radius-xl);
  background: var(--surface-strong);
  border: 1px solid var(--line);
  box-shadow: var(--shadow);
}

.reader-top {
  display: flex;
  justify-content: space-between;
  gap: 14px;
  align-items: flex-end;
}

.page-badge {
  display: inline-flex;
  padding: 6px 11px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--accent-2) 18%, transparent);
  color: color-mix(in srgb, var(--accent-2) 70%, #000);
  font-size: calc(0.9rem * var(--reader-scale));
  font-weight: 800;
}

.chapter-title {
  margin-top: 10px;
  font-size: clamp(1.25rem, 4.4vw, 1.9rem);
  line-height: 1.25;
  font-weight: 800;
  font-family: "Songti SC", "STSong", "Noto Serif SC", Georgia, serif;
}

.progress-text {
  flex: none;
  color: var(--muted);
  font-size: 0.95rem;
  font-weight: 700;
}

.progress-rail {
  width: 100%;
  height: 8px;
  margin-top: 12px;
  border-radius: 999px;
  background: color-mix(in srgb, var(--text) 10%, transparent);
  overflow: hidden;
}

.progress-fill {
  height: 100%;
  width: 0%;
  border-radius: inherit;
  background: linear-gradient(90deg, var(--accent), var(--accent-2));
  transition: width 0.3s ease;
}

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

.chapter-meta {
  color: var(--muted);
  font-size: calc(0.98rem * var(--reader-scale));
  line-height: 1.6;
  margin-bottom: 12px;
}

.video-slot {
  margin: 0 0 16px;
  border-radius: 16px;
  overflow: hidden;
  background: #0b0f14;
  aspect-ratio: 16 / 9;
  position: relative;
}

.video-slot iframe {
  display: block;
  width: 100%;
  height: 100%;
  border: 0;
}

.video-open-link {
  position: absolute;
  right: 10px;
  bottom: 10px;
  margin: 0;
  z-index: 2;
}

.video-open-link a {
  display: inline-flex;
  padding: 6px 10px;
  border-radius: 999px;
  background: rgba(0, 0, 0, 0.72);
  color: #fff;
  text-decoration: none;
  font-size: 0.82rem;
  font-weight: 700;
}

.video-missing {
  display: grid;
  place-items: center;
  height: 100%;
  padding: 18px;
  text-align: center;
  color: #d7dee7;
  font-size: 0.95rem;
  line-height: 1.6;
}

.video-missing a {
  color: #9ad4b8;
}

.lesson-body {
  display: grid;
  gap: 14px;
  padding-bottom: 8px;
}

.lesson-body p {
  margin: 0;
  color: var(--text);
  font-size: calc(1.05rem * var(--reader-scale));
  line-height: 1.85;
  white-space: pre-wrap;
  overflow-wrap: anywhere;
}

.bottom-dock {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 20;
  pointer-events: none;
  padding: 0 14px calc(12px + env(safe-area-inset-bottom));
  background: linear-gradient(180deg, transparent, color-mix(in srgb, var(--bg-c) 88%, transparent));
}

.controls {
  pointer-events: auto;
  width: min(100%, 420px);
  margin: 0 auto;
  display: grid;
  grid-template-columns: repeat(5, minmax(0, 1fr));
  gap: 8px;
}

.control-btn {
  border: 0;
  border-radius: 18px;
  aspect-ratio: 1 / 1;
  max-height: 58px;
  padding: 0;
  font: inherit;
  display: grid;
  place-items: center;
  color: inherit;
  box-shadow: inset 0 1px 0 rgba(255, 255, 255, 0.35);
}

.control-btn.secondary {
  background: color-mix(in srgb, var(--text) 8%, transparent);
  color: var(--text);
}

.control-btn.primary {
  background: linear-gradient(135deg, var(--accent), var(--accent-2));
  color: #fff;
}

.control-btn.tertiary {
  background: color-mix(in srgb, var(--accent-2) 16%, transparent);
  color: color-mix(in srgb, var(--accent-2) 75%, #000);
}

.control-btn.font-btn {
  background: color-mix(in srgb, var(--accent) 12%, transparent);
  color: var(--accent);
}

.control-btn:disabled {
  opacity: 0.4;
}

.control-icon {
  width: 26px;
  height: 26px;
  fill: none;
  stroke: currentColor;
  stroke-width: 2.3;
  stroke-linecap: round;
  stroke-linejoin: round;
}

.sr-only {
  position: absolute;
  width: 1px;
  height: 1px;
  padding: 0;
  margin: -1px;
  overflow: hidden;
  clip: rect(0, 0, 0, 0);
  white-space: nowrap;
  border: 0;
}

.hidden {
  display: none !important;
}

.catalog-modal {
  position: fixed;
  inset: 0;
  z-index: 50;
  display: grid;
  justify-items: end;
  align-items: center;
  padding: 14px;
}

.catalog-backdrop {
  position: absolute;
  inset: 0;
  background: rgba(14, 18, 26, 0.28);
}

.catalog-sheet {
  position: relative;
  width: min(94vw, 400px);
  max-height: min(78vh, 720px);
  overflow: auto;
  background: var(--surface);
  border-radius: 22px;
  box-shadow: var(--shadow);
  padding: 14px;
  border: 1px solid var(--line);
  z-index: 1;
}

.catalog-head {
  display: flex;
  justify-content: space-between;
  gap: 12px;
  align-items: flex-start;
  margin-bottom: 12px;
}

.catalog-head h3 {
  margin: 0;
  font-size: 1.25rem;
}

.catalog-head p {
  margin-top: 4px;
  color: var(--muted);
  font-size: 0.88rem;
}

.close-btn {
  border: 0;
  border-radius: 999px;
  padding: 8px 12px;
  background: color-mix(in srgb, var(--text) 8%, transparent);
  color: var(--text);
  font: inherit;
  font-weight: 700;
}

.catalog-list {
  display: grid;
  gap: 10px;
}

.catalog-chapter {
  display: grid;
  gap: 6px;
}

.catalog-chapter-label {
  position: sticky;
  top: 0;
  z-index: 1;
  padding: 8px 4px;
  background: color-mix(in srgb, var(--surface) 92%, transparent);
  color: var(--accent);
  font-size: 0.88rem;
  font-weight: 800;
}

.catalog-item {
  width: 100%;
  border: 1px solid var(--line);
  border-radius: 14px;
  background: color-mix(in srgb, var(--surface-strong) 88%, transparent);
  color: inherit;
  text-align: left;
  padding: 10px 12px;
  font: inherit;
  display: grid;
  gap: 2px;
}

.catalog-item strong {
  font-size: 0.95rem;
  line-height: 1.35;
}

.catalog-item span {
  color: var(--muted);
  font-size: 0.8rem;
}

.catalog-item.is-active {
  border-color: color-mix(in srgb, var(--accent) 45%, transparent);
  background: color-mix(in srgb, var(--accent) 10%, transparent);
}

.control-btn:focus-visible,
.close-btn:focus-visible,
.catalog-item:focus-visible,
.back-link:focus-visible {
  outline: 3px solid color-mix(in srgb, var(--accent) 35%, transparent);
  outline-offset: 2px;
}

@media (min-width: 768px) {
  .app-shell {
    padding: 22px 22px calc(96px + env(safe-area-inset-bottom));
  }

  .reader {
    padding: 22px;
  }
}