:root {
  --bg: #0f1421;
  --fg: #d6d8e0;
  --panel: #161c2c;
  --border: #d6d8e026;
  --accent: #4f8cff;
  --muted: #9aa0ae;
  --content-max: 760px;
}
html[data-theme='light'] {
  --bg: #f6f6f4;
  --fg: #1c1e21;
  --panel: #ffffff;
  --border: #0000001f;
  --accent: #2563eb;
  --muted: #5c6270;
}
html[data-theme='sepia'] {
  --bg: #f4ecd8;
  --fg: #433422;
  --panel: #efe4c8;
  --border: #43342226;
  --accent: #8a5a2b;
  --muted: #7a6a52;
}
html[data-theme='midnight'] {
  --bg: #05070d;
  --fg: #b9bec9;
  --panel: #0b0f18;
  --border: #b9bec91f;
  --accent: #7aa2ff;
  --muted: #6b7280;
}
html[data-theme='forest'] {
  --bg: #0d1512;
  --fg: #cfe3d5;
  --panel: #12201a;
  --border: #cfe3d521;
  --accent: #4caf7d;
  --muted: #8aa396;
}

* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--fg);
  font-family: 'Roboto', system-ui, -apple-system, 'Segoe UI', sans-serif;
  line-height: 1.7;
  transition: background 0.25s, color 0.25s;
}
a { color: var(--accent); text-decoration: none; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 50;
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 0.65rem 1rem;
  background: color-mix(in srgb, var(--panel) 88%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--border);
}
.brand { font-weight: 700; letter-spacing: 0.01em; color: var(--fg); }
.nav-links { display: flex; gap: 1rem; }
.nav-links a { color: var(--muted); font-size: 0.95rem; }
.nav-links a.active, .nav-links a:hover { color: var(--fg); }

main { padding: 1rem 1rem 5rem; }

.reader-head { max-width: var(--content-max); margin: 1.5rem auto 0.5rem; }
.reader-head h1 { margin: 0; font-size: 1.6rem; line-height: 1.3; }
.reader-head .sub { margin: 0.35rem 0 0; color: var(--muted); font-size: 0.9rem; }

.reader-toolbar {
  max-width: var(--content-max);
  margin: 0.9rem auto;
  padding: 0.55rem;
  display: flex;
  flex-wrap: wrap;
  gap: 0.5rem;
  align-items: center;
  border-top: 1px solid var(--border);
  border-bottom: 1px solid var(--border);
}
.reader-toolbar .group { display: inline-flex; gap: 0.25rem; }
button, select, input[type='search'] {
  background: color-mix(in srgb, var(--fg) 7%, transparent);
  color: var(--fg);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 0.35rem 0.6rem;
  font-size: 0.85rem;
  cursor: pointer;
}
button:hover { background: color-mix(in srgb, var(--fg) 14%, transparent); }
button.active-tts { background: var(--accent); color: #fff; border-color: var(--accent); }

.content {
  max-width: var(--content-max);
  margin: 1.25rem auto;
  font-size: var(--font-size, 18px);
  line-height: var(--line-height, 1.8);
}
.content p { margin: 0 0 1.1em; }
.content[data-font='serif'] { font-family: Georgia, 'Times New Roman', serif; }
.content[data-font='mono'] { font-family: 'SF Mono', Menlo, Consolas, monospace; font-size: calc(var(--font-size, 18px) * 0.92); }
.content[data-font='dyslexic'] { font-family: Verdana, 'Trebuchet MS', sans-serif; letter-spacing: 0.03em; word-spacing: 0.12em; }
html[data-width='narrow'] .content, html[data-width='narrow'] .reader-head, html[data-width='narrow'] .reader-toolbar { max-width: 560px; }
html[data-width='wide'] .content, html[data-width='wide'] .reader-head, html[data-width='wide'] .reader-toolbar { max-width: 960px; }
html[data-width='full'] .content, html[data-width='full'] .reader-head, html[data-width='full'] .reader-toolbar { max-width: 1200px; }

.chapter-nav {
  max-width: var(--content-max);
  margin: 2rem auto 1rem;
  display: flex;
  gap: 0.6rem;
  flex-wrap: wrap;
  justify-content: space-between;
}
.btn {
  display: inline-block;
  padding: 0.6rem 1rem;
  border-radius: 10px;
  border: 1px solid var(--border);
  background: var(--panel);
  color: var(--fg);
  font-size: 0.9rem;
  max-width: 45%;
  overflow: hidden;
  text-overflow: ellipsis;
  white-space: nowrap;
}
.btn:hover { border-color: var(--accent); }
.btn.primary { background: var(--accent); border-color: var(--accent); color: #fff; }
.btn.disabled { opacity: 0.4; pointer-events: none; }
.select-wrap { max-width: var(--content-max); margin: 0 auto; }
#chapter-select { width: 100%; padding: 0.55rem; }

.toc { max-width: 860px; margin: 0 auto; }
.toc-controls {
  display: flex;
  gap: 0.75rem;
  align-items: center;
  flex-wrap: wrap;
  margin: 1rem 0;
  position: sticky;
  top: 52px;
  background: var(--bg);
  padding: 0.5rem 0;
  z-index: 10;
}
#toc-search { flex: 1; min-width: 200px; padding: 0.55rem 0.8rem; }
.toc-controls label { color: var(--muted); font-size: 0.9rem; display: flex; gap: 0.4rem; align-items: center; }
.toc-list { list-style: none; margin: 0; padding: 0; }
.toc-list li a {
  display: flex;
  gap: 0.75rem;
  align-items: baseline;
  padding: 0.55rem 0.75rem;
  border-bottom: 1px solid var(--border);
  color: var(--fg);
}
.toc-list li a:hover { background: color-mix(in srgb, var(--fg) 6%, transparent); }
.toc-list .num { color: var(--muted); font-size: 0.8rem; min-width: 3.2em; }
.toc-list li.read a { color: var(--muted); }
.toc-list li.read .num::after { content: ' ✓'; color: var(--accent); }

.home { max-width: 900px; margin: 0 auto; }
.hero { display: flex; gap: 2rem; margin-top: 2rem; flex-wrap: wrap; }
.cover { width: 220px; height: auto; border-radius: 12px; box-shadow: 0 8px 30px rgb(0 0 0 / 0.35); }
.hero-info { flex: 1; min-width: 260px; }
.hero-info h1 { margin: 0 0 0.25rem; font-size: 2rem; }
.hero-info .alt { color: var(--muted); margin: 0 0 0.5rem; }
.hero-info .meta { color: var(--muted); font-size: 0.9rem; }
.hero-info .summary { line-height: 1.75; }
.actions { display: flex; gap: 0.75rem; margin-top: 1rem; flex-wrap: wrap; }
.actions .btn { max-width: none; }

#tts-status { font-size: 0.8rem; color: var(--muted); }

@media (max-width: 640px) {
  .btn { max-width: 100%; flex: 1; text-align: center; }
  .cover { width: 150px; }
  .hero { justify-content: center; text-align: left; }
}