:root {
  color-scheme: light;
  --bg: #f6f1e8;
  --panel: rgba(255, 252, 246, 0.94);
  --text: #2a241d;
  --muted: #7b6f62;
  --line: rgba(60, 47, 35, 0.1);
  --accent: #8b5e3c;
  --accent-strong: #6f4527;
  --shadow: 0 20px 50px rgba(56, 41, 28, 0.10);
  --reader-width: 980px;
  --font-size: 20px;
  --bg-image: radial-gradient(circle at top, rgba(255,255,255,0.8), transparent 42%), linear-gradient(180deg, #f8f4ec 0%, #f2eadf 100%);
}

body[data-theme='dark'] {
  color-scheme: dark;
  --bg: #171310;
  --panel: rgba(28, 23, 19, 0.95);
  --text: #efe5d7;
  --muted: #b7a998;
  --line: rgba(255, 240, 220, 0.08);
  --accent: #d8ab7b;
  --accent-strong: #f1c89c;
  --shadow: 0 24px 60px rgba(0, 0, 0, 0.35);
  --bg-image: radial-gradient(circle at top, rgba(87, 61, 41, 0.25), transparent 35%), linear-gradient(180deg, #15110f 0%, #1d1714 100%);
}

* { box-sizing: border-box; }
html, body { margin: 0; min-height: 100%; }
body {
  font-family: "PingFang SC", "Hiragino Sans GB", "Noto Serif SC", serif;
  background: var(--bg-image);
  color: var(--text);
}
button { font: inherit; }

.app-shell {
  min-height: 100vh;
  display: grid;
  grid-template-columns: 320px 1fr;
}

.sidebar {
  position: sticky;
  top: 0;
  height: 100vh;
  padding: 28px 20px;
  background: var(--panel);
  border-right: 1px solid var(--line);
  box-shadow: var(--shadow);
  backdrop-filter: blur(18px);
  overflow: auto;
}

.eyebrow {
  margin: 0 0 10px;
  color: var(--accent);
  font-size: 13px;
  letter-spacing: 0.12em;
  text-transform: uppercase;
}

.sidebar h1,
.chapter-meta h2 {
  margin: 0;
  line-height: 1.2;
}

.book-subtitle,
.book-desc,
.saved-pill,
.toc-title-row,
.chapter-list button,
.reader-toolbar,
.chapter-footer,
.ghost-btn,
.nav-btn,
.page-chip,
.chapter-submeta,
.page-note {
  font-family: "PingFang SC", "Helvetica Neue", sans-serif;
}

.book-subtitle,
.book-desc,
.saved-pill,
.chapter-submeta,
.page-note {
  color: var(--muted);
}

.book-subtitle,
.book-desc {
  line-height: 1.7;
}

.saved-pill {
  display: inline-flex;
  margin-top: 16px;
  padding: 8px 12px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: rgba(139, 94, 60, 0.08);
  font-size: 13px;
}

.toc-wrap { margin-top: 28px; }
.toc-title-row {
  display: flex;
  justify-content: space-between;
  align-items: center;
  color: var(--muted);
  font-size: 14px;
}
.progress-track {
  margin-top: 10px;
  height: 8px;
  background: rgba(128, 110, 91, 0.14);
  border-radius: 999px;
  overflow: hidden;
}
.progress-bar {
  width: 0%;
  height: 100%;
  background: linear-gradient(90deg, var(--accent), var(--accent-strong));
}
.chapter-list {
  display: grid;
  gap: 10px;
  margin-top: 18px;
}
.chapter-list button {
  text-align: left;
  border: 1px solid var(--line);
  background: transparent;
  color: var(--text);
  padding: 12px 14px;
  border-radius: 14px;
  cursor: pointer;
  transition: 160ms ease;
}
.chapter-list button:hover,
.chapter-list button.active {
  border-color: rgba(139, 94, 60, 0.45);
  background: rgba(139, 94, 60, 0.10);
}

.reader {
  min-width: 0;
  padding: 24px 18px 34px;
}
.reader-toolbar,
.chapter-footer {
  max-width: var(--reader-width);
  margin: 0 auto;
  display: flex;
  justify-content: space-between;
  align-items: center;
  gap: 12px;
}
.toolbar-left,
.toolbar-actions {
  display: flex;
  gap: 10px;
  align-items: center;
}
.page-chip {
  display: inline-flex;
  padding: 10px 14px;
  border-radius: 999px;
  border: 1px solid var(--line);
  background: var(--panel);
  white-space: nowrap;
}
.ghost-btn,
.nav-btn {
  border: 1px solid var(--line);
  background: var(--panel);
  color: var(--text);
  border-radius: 999px;
  padding: 10px 16px;
  cursor: pointer;
}
.nav-btn.primary {
  background: var(--accent);
  color: #fffaf5;
  border-color: transparent;
}
.nav-btn:disabled {
  opacity: 0.45;
  cursor: not-allowed;
}
.reader-article {
  max-width: var(--reader-width);
  margin: 18px auto;
}
.page-frame {
  padding: 28px clamp(18px, 3vw, 36px) 22px;
  background: var(--panel);
  border: 1px solid var(--line);
  border-radius: 28px;
  box-shadow: var(--shadow);
}
.chapter-meta {
  margin-bottom: 18px;
}
.chapter-submeta {
  margin: 10px 0 0;
  font-size: 14px;
}
.chapter-content {
  --page-gap: 34px;
  position: relative;
  overflow: hidden;
  height: clamp(560px, calc(100vh - 220px), 980px);
  border-top: 1px solid rgba(127, 108, 88, 0.12);
  padding-top: 18px;
}
.chapter-content::before,
.chapter-content::after {
  content: "";
  position: absolute;
  top: 0;
  bottom: 0;
  width: 36px;
  z-index: 2;
  pointer-events: none;
}
.chapter-content::before {
  left: 0;
  background: linear-gradient(90deg, var(--panel), rgba(255,255,255,0));
}
.chapter-content::after {
  right: 0;
  background: linear-gradient(270deg, var(--panel), rgba(255,255,255,0));
}
body[data-theme='dark'] .chapter-content::before {
  background: linear-gradient(90deg, var(--panel), rgba(0,0,0,0));
}
body[data-theme='dark'] .chapter-content::after {
  background: linear-gradient(270deg, var(--panel), rgba(0,0,0,0));
}
.chapter-flow {
  height: 100%;
  column-fill: auto;
  column-gap: var(--page-gap);
  transform: translateX(0);
  transition: transform 220ms ease;
  will-change: transform;
}
.chapter-flow p {
  margin: 0 0 1.05em;
  font-size: var(--font-size);
  line-height: 2.02;
  letter-spacing: 0.012em;
  text-indent: 2em;
  break-inside: auto;
  orphans: 3;
  widows: 3;
}
.tap-zone {
  position: absolute;
  top: 0;
  bottom: 0;
  width: 18%;
  z-index: 3;
  border: 0;
  background: transparent;
  cursor: pointer;
}
.tap-zone-left { left: 0; }
.tap-zone-right { right: 0; }
.tap-zone:hover {
  background: rgba(139, 94, 60, 0.05);
}
.page-note {
  padding: 10px 6px 0;
  text-align: center;
  font-size: 13px;
}

@media (max-width: 960px) {
  .app-shell { grid-template-columns: 1fr; }
  .sidebar {
    position: fixed;
    left: 0;
    top: 0;
    bottom: 0;
    width: min(84vw, 340px);
    z-index: 20;
    transform: translateX(-105%);
    transition: transform 180ms ease;
  }
  body.sidebar-open .sidebar { transform: translateX(0); }
  .chapter-content {
    height: clamp(520px, calc(100vh - 205px), 900px);
  }
}

@media (max-width: 640px) {
  .reader { padding: 12px 8px 24px; }
  .reader-toolbar,
  .chapter-footer {
    flex-wrap: wrap;
  }
  .toolbar-left,
  .toolbar-actions {
    width: 100%;
    justify-content: space-between;
  }
  .reader-article { margin-top: 14px; }
  .page-frame { padding: 20px 14px 16px; border-radius: 20px; }
  .chapter-content {
    --page-gap: 22px;
    height: clamp(470px, calc(100vh - 188px), 84vh);
    padding-top: 14px;
  }
  .chapter-flow p {
    line-height: 1.92;
  }
  .tap-zone {
    width: 22%;
  }
}