:root {
  --bg: #f4f0e7;
  --paper: #fbf8f1;
  --text: #27251f;
  --muted: #777064;
  --line: #d8d0c1;
  --accent: #324f3c;
  --sidebar: #ece6da;
  --shadow: 0 18px 60px rgba(34, 30, 23, .08);
  --reader-size: 19px;
  color-scheme: light;
}
:root[data-theme="dark"] {
  --bg: #151713;
  --paper: #1c1f1a;
  --text: #e7e3d8;
  --muted: #aaa497;
  --line: #363a32;
  --accent: #a7c7ac;
  --sidebar: #181b17;
  --shadow: none;
  color-scheme: dark;
}
* { box-sizing: border-box; }
html { scroll-behavior: smooth; }
body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: ui-serif, "Iowan Old Style", "Noto Serif CJK SC", "Songti SC", Georgia, serif;
}
button { font: inherit; }
#progress {
  position: fixed;
  z-index: 100;
  left: 0;
  top: 0;
  height: 3px;
  width: 0;
  background: var(--accent);
}
.app { min-height: 100vh; }
.sidebar {
  position: fixed;
  inset: 0 auto 0 0;
  width: 300px;
  padding: 38px 24px 26px;
  overflow-y: auto;
  background: var(--sidebar);
  border-right: 1px solid var(--line);
}
.brand { padding: 0 10px 30px; border-bottom: 1px solid var(--line); }
.eyebrow {
  font: 600 11px/1.2 ui-sans-serif, system-ui, sans-serif;
  letter-spacing: .22em;
  color: var(--muted);
}
.brand h1 { margin: 10px 0 4px; font-size: 31px; font-weight: 600; letter-spacing: .08em; }
.subtitle { color: var(--muted); font-style: italic; }
.chapter-list { padding: 22px 0; }
.chapter-link {
  display: block;
  width: 100%;
  border: 0;
  background: transparent;
  color: var(--muted);
  text-align: left;
  padding: 10px 12px;
  border-radius: 8px;
  cursor: pointer;
  line-height: 1.45;
}
.chapter-link:hover { color: var(--text); background: rgba(127,127,127,.08); }
.chapter-link.active {
  color: var(--text);
  background: var(--paper);
  box-shadow: inset 3px 0 0 var(--accent);
}
.chapter-link .n {
  display: inline-block;
  width: 27px;
  font: 600 11px ui-sans-serif, system-ui, sans-serif;
  color: var(--muted);
}
.sidebar-note {
  padding: 18px 10px 0;
  border-top: 1px solid var(--line);
  font: 12px/1.6 ui-sans-serif, system-ui, sans-serif;
  color: var(--muted);
}
.main { margin-left: 300px; min-height: 100vh; }
.toolbar {
  position: sticky;
  top: 0;
  z-index: 30;
  height: 66px;
  display: flex;
  align-items: center;
  gap: 18px;
  padding: 0 26px;
  background: color-mix(in srgb, var(--bg) 86%, transparent);
  backdrop-filter: blur(14px);
  border-bottom: 1px solid color-mix(in srgb, var(--line) 70%, transparent);
}
.toolbar-title { flex: 1; font: 12px ui-sans-serif, system-ui, sans-serif; color: var(--muted); }
.toolbar-actions { display: flex; align-items: center; gap: 8px; }
.segmented {
  display: flex;
  padding: 3px;
  border: 1px solid var(--line);
  border-radius: 10px;
}
.segmented button, .icon-btn {
  border: 0;
  background: transparent;
  color: var(--muted);
  cursor: pointer;
}
.segmented button { padding: 6px 10px; border-radius: 7px; font: 12px ui-sans-serif, system-ui, sans-serif; }
.segmented button.active { background: var(--paper); color: var(--text); box-shadow: 0 1px 4px rgba(0,0,0,.08); }
.icon-btn { min-width: 34px; height: 34px; border-radius: 8px; font: 13px ui-sans-serif, system-ui, sans-serif; }
.icon-btn:hover { background: rgba(127,127,127,.1); color: var(--text); }
.menu-btn { display: none; font-size: 18px; }
.reader {
  width: min(820px, calc(100% - 48px));
  margin: 0 auto;
  padding: 78px 0 110px;
}
.reader-head { margin-bottom: 54px; text-align: center; }
.chapter-number {
  font: 600 11px ui-sans-serif, system-ui, sans-serif;
  letter-spacing: .2em;
  color: var(--accent);
}
.reader-head h2 {
  margin: 14px 0 8px;
  font-size: clamp(34px, 5vw, 52px);
  font-weight: 600;
  line-height: 1.12;
}
.chapter-title-alt { color: var(--muted); font-size: 15px; font-style: italic; }
.content {
  font-size: var(--reader-size);
  line-height: 1.95;
  letter-spacing: .01em;
}
.content p { margin: 0 0 1.28em; }
.content hr {
  width: 46px;
  border: 0;
  border-top: 1px solid var(--line);
  margin: 3.4em auto;
}
.content strong { font-weight: 700; }
.content em { color: color-mix(in srgb, var(--text) 82%, var(--muted)); }
.chapter-nav {
  margin-top: 70px;
  padding-top: 24px;
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  gap: 16px;
}
.chapter-nav button {
  border: 1px solid var(--line);
  background: var(--paper);
  color: var(--text);
  padding: 11px 16px;
  border-radius: 10px;
  cursor: pointer;
}
.chapter-nav button:disabled { opacity: .3; cursor: default; }
footer {
  width: min(820px, calc(100% - 48px));
  margin: 0 auto;
  padding: 0 0 34px;
  color: var(--muted);
  border-top: 1px solid var(--line);
  display: flex;
  justify-content: space-between;
  font: 11px/3 ui-sans-serif, system-ui, sans-serif;
}
.overlay { display: none; }

@media (max-width: 880px) {
  .sidebar {
    z-index: 70;
    transform: translateX(-102%);
    transition: transform .22s ease;
    box-shadow: var(--shadow);
  }
  .sidebar.open { transform: translateX(0); }
  .main { margin-left: 0; }
  .menu-btn { display: inline-grid; place-items: center; }
  .toolbar { padding: 0 14px; }
  .toolbar-title { display: none; }
  .toolbar-actions { margin-left: auto; }
  .reader { width: min(680px, calc(100% - 34px)); padding-top: 50px; }
  .overlay {
    position: fixed; inset: 0; z-index: 60;
    background: rgba(0,0,0,.28);
  }
  .overlay.show { display: block; }
}
@media (max-width: 560px) {
  .toolbar-actions .icon-btn:not(#theme-btn) { display: none; }
  .reader-head { margin-bottom: 42px; }
  .content { line-height: 1.88; }
  footer { width: calc(100% - 34px); }
}