/* 擴展模型白話讀本 — 安靜的長文閱讀系統 */

:root {
  --paper: #FAF8F4;
  --surface: #FFFFFF;
  --surface-sunk: #F3F0E9;
  --ink: #1B1A17;
  --ink-dim: #6B675F;
  --line: #E2DDD2;
  --indigo: #12615F;
  --indigo-soft: #DFEDEC;
  --amber: #9C6B15;
  --amber-soft: #F7EEDC;
  --rose: #A33A3A;
  --rose-soft: #F6E4E2;
  --radius: 10px;
  --measure: 34rem;
  --serif: "Iowan Old Style", "Source Serif 4", Georgia, "Noto Serif TC", "Songti TC", "PingFang TC", serif;
  --sans: -apple-system, BlinkMacSystemFont, "Segoe UI", "PingFang TC", "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  --mono: ui-monospace, "SF Mono", Menlo, Consolas, monospace;
  color-scheme: light;
}

@media (prefers-color-scheme: dark) {
  :root:not([data-theme="light"]) {
    --paper: #14161A;
    --surface: #1B1E23;
    --surface-sunk: #22262C;
    --ink: #E8E4DC;
    --ink-dim: #9A958B;
    --line: #2E333A;
    --indigo: #6FC7BF;
    --indigo-soft: #1D3A38;
    --amber: #D9A85A;
    --amber-soft: #33291A;
    --rose: #E08B85;
    --rose-soft: #3A2422;
    color-scheme: dark;
  }
}

:root[data-theme="dark"] {
  --paper: #14161A;
  --surface: #1B1E23;
  --surface-sunk: #22262C;
  --ink: #E8E4DC;
  --ink-dim: #9A958B;
  --line: #2E333A;
  --indigo: #6FC7BF;
  --indigo-soft: #1D3A38;
  --amber: #D9A85A;
  --amber-soft: #33291A;
  --rose: #E08B85;
  --rose-soft: #3A2422;
  color-scheme: dark;
}

* { box-sizing: border-box; }

html { -webkit-text-size-adjust: 100%; }

body {
  margin: 0;
  background: var(--paper);
  color: var(--ink);
  font-family: var(--serif);
  font-size: 17px;
  line-height: 1.78;
  overflow-wrap: break-word;
}

button, input, select { font-family: inherit; }
button { cursor: pointer; }

a { color: var(--indigo); text-underline-offset: 3px; }

:focus-visible {
  outline: 2px solid var(--indigo);
  outline-offset: 2px;
  border-radius: 4px;
}

.skip-link {
  position: absolute;
  left: -9999px;
  top: 0;
  z-index: 50;
  padding: 10px 16px;
  background: var(--indigo);
  color: #FFF;
  border-radius: 0 0 var(--radius) 0;
}
.skip-link:focus { left: 0; }

/* ---------- 頂部列 ---------- */

.topbar {
  position: sticky;
  top: 0;
  z-index: 20;
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 12px;
  height: 52px;
  padding: 0 22px;
  background: color-mix(in srgb, var(--paper) 92%, transparent);
  backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--line);
}

.brand {
  display: flex;
  align-items: center;
  gap: 10px;
  text-decoration: none;
  color: inherit;
  min-width: 0;
}

.brand-mark {
  flex: none;
  width: 30px;
  height: 30px;
  display: grid;
  place-items: center;
  border-radius: 8px;
  background: var(--indigo);
  color: #FAF8F4;
  font-size: 17px;
}

.brand-text { display: flex; flex-direction: column; min-width: 0; }
.brand-text strong { font-size: 15px; letter-spacing: .02em; white-space: nowrap; }
.brand-text small {
  font-family: var(--sans);
  font-size: 11px;
  color: var(--ink-dim);
  white-space: nowrap;
  overflow: hidden;
  text-overflow: ellipsis;
}

.topbar-actions { display: flex; align-items: center; gap: 8px; flex: none; }

.progress-pill {
  font-family: var(--mono);
  font-size: 12px;
  padding: 4px 10px;
  border-radius: 999px;
  background: var(--indigo-soft);
  color: var(--indigo);
  white-space: nowrap;
}

.icon-btn {
  width: 32px;
  height: 32px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink-dim);
  font-size: 15px;
  line-height: 1;
}
.icon-btn:hover { color: var(--indigo); border-color: var(--indigo); }

/* ---------- 版面 ---------- */

.view {
  max-width: 41rem;
  margin: 0 auto;
  padding: 26px 22px 72px;
  outline: none;
}

.sitefoot {
  max-width: 41rem;
  margin: 0 auto;
  padding: 22px 22px 48px;
  border-top: 1px solid var(--line);
  font-family: var(--sans);
  font-size: 12px;
  line-height: 1.7;
  color: var(--ink-dim);
}
.sitefoot p { margin: 0 0 6px; }

/* ---------- 首頁 ---------- */

.home-lede { margin: 0 0 26px; }
.home-lede h1 {
  font-size: clamp(26px, 5.4vw, 34px);
  line-height: 1.28;
  margin: 0 0 10px;
  letter-spacing: -.01em;
}
.home-lede p {
  margin: 0 0 8px;
  color: var(--ink-dim);
  max-width: var(--measure);
}

.resume-card {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 14px;
  flex-wrap: wrap;
  margin: 0 0 26px;
  padding: 14px 16px;
  border: 1px solid var(--indigo);
  border-left-width: 3px;
  border-radius: var(--radius);
  background: var(--indigo-soft);
}
.resume-card .resume-label {
  font-family: var(--sans);
  font-size: 11px;
  letter-spacing: .1em;
  text-transform: uppercase;
  color: var(--indigo);
  display: block;
  margin-bottom: 2px;
}
.resume-card .resume-where { font-size: 15px; line-height: 1.5; }

.btn {
  font-family: var(--sans);
  font-size: 14px;
  padding: 9px 16px;
  border-radius: 8px;
  border: 1px solid var(--indigo);
  background: var(--indigo);
  color: #FFF;
  text-decoration: none;
  display: inline-block;
  white-space: nowrap;
}
.btn.ghost { background: transparent; color: var(--indigo); }
.btn.ghost:hover { background: var(--indigo-soft); }

.toc-head {
  display: flex;
  align-items: baseline;
  justify-content: space-between;
  gap: 12px;
  margin: 0 0 6px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
}
.toc-head h2 { font-size: 14px; margin: 0; letter-spacing: .04em; }
.toc-head span { font-family: var(--sans); font-size: 12px; color: var(--ink-dim); }

.toc { list-style: none; margin: 0; padding: 0; }

.toc-item {
  display: grid;
  grid-template-columns: 2.1rem 1fr auto;
  align-items: baseline;
  gap: 12px;
  padding: 13px 4px;
  border-bottom: 1px solid var(--line);
  text-decoration: none;
  color: inherit;
}
.toc-item:hover { background: var(--surface-sunk); }
.toc-num {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-dim);
}
.toc-title { line-height: 1.45; }
.toc-title b { font-weight: 600; font-size: 16.5px; }
.toc-title small {
  display: block;
  font-family: var(--sans);
  font-size: 11.5px;
  color: var(--ink-dim);
  margin-top: 2px;
}
.toc-state {
  font-family: var(--sans);
  font-size: 11px;
  color: var(--ink-dim);
  white-space: nowrap;
}
.toc-item.done .toc-state { color: var(--indigo); }

/* ---------- 章節 ---------- */

.ch-nav {
  position: sticky;
  top: 52px;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 8px;
  height: 50px;
  margin: -26px -22px 18px;
  padding: 0 22px;
  background: color-mix(in srgb, var(--paper) 94%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}
.ch-nav .nav-link {
  font-family: var(--sans);
  font-size: 13px;
  text-decoration: none;
  color: var(--ink-dim);
  padding: 5px 8px;
  border-radius: 6px;
}
.ch-nav .nav-link:hover { color: var(--indigo); background: var(--indigo-soft); }
.ch-nav .nav-spacer { flex: 1; }
.ch-nav .nav-pos { font-family: var(--mono); font-size: 12px; color: var(--ink-dim); }

.ch-head { margin: 0 0 26px; }
.ch-kicker {
  font-family: var(--sans);
  font-size: 11px;
  letter-spacing: .14em;
  text-transform: uppercase;
  color: var(--ink-dim);
  margin: 0 0 8px;
}
.ch-head h1 {
  font-size: clamp(25px, 5.2vw, 33px);
  line-height: 1.3;
  margin: 0 0 6px;
  letter-spacing: -.01em;
}
.ch-head .ch-sub {
  margin: 0;
  font-family: var(--sans);
  font-size: 13px;
  color: var(--ink-dim);
}

.analogy {
  margin: 0 0 30px;
  padding: 16px 18px;
  border-radius: var(--radius);
  background: var(--amber-soft);
  border: 1px solid color-mix(in srgb, var(--amber) 28%, transparent);
}
.analogy h2 {
  font-family: var(--sans);
  font-size: 13px;
  letter-spacing: .04em;
  margin: 0 0 8px;
  color: var(--amber);
}
.analogy p { margin: 0 0 10px; }
.analogy p:last-child { margin-bottom: 0; }

section.ch-section { margin: 0 0 32px; scroll-margin-top: 106px; }
section.ch-section > h2 {
  font-size: 19px;
  line-height: 1.4;
  margin: 0 0 12px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
}
section.ch-section p { margin: 0 0 14px; max-width: var(--measure); }

code {
  font-family: var(--mono);
  font-size: .87em;
  padding: 1px 5px;
  border-radius: 4px;
  background: var(--surface-sunk);
}

.terms { margin: 14px 0 0; padding: 0; list-style: none; }
.term {
  display: grid;
  grid-template-columns: minmax(0, 1fr);
  gap: 2px;
  padding: 9px 12px;
  border-left: 2px solid var(--indigo);
  background: var(--surface);
  border-radius: 0 6px 6px 0;
  margin-bottom: 6px;
  font-size: 14.5px;
  line-height: 1.6;
}
.term .term-plain { color: var(--ink); }
.term .term-formal {
  font-family: var(--sans);
  font-size: 12.5px;
  color: var(--ink-dim);
}
.term .term-formal b { color: var(--indigo); font-weight: 600; }

/* ---------- 圖解 ---------- */

.diagram {
  margin: 0 0 32px;
  padding: 16px;
  border: 1px solid var(--line);
  border-radius: var(--radius);
  background: var(--surface);
}
.diagram h2 {
  font-family: var(--sans);
  font-size: 13px;
  letter-spacing: .04em;
  margin: 0 0 4px;
  color: var(--ink-dim);
}
.diagram .diagram-caption {
  font-family: var(--sans);
  font-size: 12.5px;
  line-height: 1.65;
  color: var(--ink-dim);
  margin: 10px 0 0;
}
.diagram-controls {
  display: flex;
  flex-wrap: wrap;
  gap: 8px;
  align-items: center;
  margin: 0 0 12px;
  font-family: var(--sans);
  font-size: 12.5px;
}
.diagram-controls label { display: flex; align-items: center; gap: 6px; color: var(--ink-dim); }
.diagram-controls input[type="range"] { width: 148px; accent-color: var(--indigo); }
.diagram-controls .readout {
  font-family: var(--mono);
  font-size: 12px;
  color: var(--indigo);
  background: var(--indigo-soft);
  padding: 2px 7px;
  border-radius: 5px;
}
.chip {
  font-family: var(--sans);
  font-size: 12px;
  padding: 5px 11px;
  border: 1px solid var(--line);
  border-radius: 999px;
  background: var(--surface);
  color: var(--ink-dim);
}
.chip.selected { background: var(--indigo); border-color: var(--indigo); color: #FFF; }

.diagram svg { display: block; width: 100%; height: auto; overflow: visible; }
.diagram .d-label { font-family: var(--sans); font-size: 11px; fill: var(--ink-dim); }
.diagram .d-label-strong { font-family: var(--sans); font-size: 11.5px; fill: var(--ink); font-weight: 600; }
.diagram .d-axis { stroke: var(--line); stroke-width: 1; }
.diagram .d-grid { stroke: var(--line); stroke-width: 1; stroke-dasharray: 3 4; }
.diagram .d-curve { fill: none; stroke: var(--indigo); stroke-width: 2.5; stroke-linejoin: round; }
.diagram .d-hot { fill: none; stroke: var(--rose); stroke-width: 2; }
.diagram .d-fill { fill: var(--indigo-soft); }
.diagram .d-box { fill: var(--surface-sunk); stroke: var(--line); stroke-width: 1; }
.diagram .d-box-on { fill: var(--indigo-soft); stroke: var(--indigo); stroke-width: 1.5; }
.diagram .d-box-hot { fill: var(--amber-soft); stroke: var(--amber); stroke-width: 1.5; }
.diagram .d-box-alt { fill: var(--rose-soft); stroke: var(--rose); stroke-width: 1.5; }

/* ---------- 測驗 ---------- */

.quiz { margin: 0 0 30px; }
.quiz > h2 {
  font-size: 19px;
  margin: 0 0 4px;
  padding-bottom: 6px;
  border-bottom: 1px solid var(--line);
}
.quiz-score {
  font-family: var(--sans);
  font-size: 12.5px;
  color: var(--ink-dim);
  margin: 0 0 16px;
}

.q { margin: 0 0 20px; }
.q-stem { margin: 0 0 10px; font-size: 16.5px; line-height: 1.65; }
.q-stem .q-num { font-family: var(--mono); font-size: 12px; color: var(--ink-dim); margin-right: 6px; }

.q-options { display: grid; gap: 7px; }
.q-opt {
  display: flex;
  gap: 9px;
  align-items: flex-start;
  width: 100%;
  text-align: left;
  padding: 10px 13px;
  border: 1px solid var(--line);
  border-radius: 8px;
  background: var(--surface);
  color: var(--ink);
  font-size: 15px;
  line-height: 1.6;
}
.q-opt:hover:not(:disabled) { border-color: var(--indigo); }
.q-opt:disabled { cursor: default; }
.q-opt .opt-key {
  flex: none;
  font-family: var(--mono);
  font-size: 12px;
  color: var(--ink-dim);
  padding-top: 2px;
}
.q-opt.correct { background: var(--indigo-soft); border-color: var(--indigo); }
.q-opt.correct .opt-key { color: var(--indigo); }
.q-opt.wrong { background: var(--rose-soft); border-color: var(--rose); }
.q-opt.wrong .opt-key { color: var(--rose); }

.q-explain {
  margin: 9px 0 0;
  padding: 10px 13px;
  border-radius: 8px;
  background: var(--surface-sunk);
  font-size: 14.5px;
  line-height: 1.7;
}
.q-explain b { color: var(--indigo); }
.q-explain[hidden] { display: none; }

/* ---------- 章末 ---------- */

.ch-end {
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: center;
  justify-content: space-between;
  padding-top: 20px;
  border-top: 1px solid var(--line);
}
.ch-end .ch-end-nav { display: flex; gap: 8px; flex-wrap: wrap; }
.mark-done[data-done="1"] { background: var(--indigo-soft); color: var(--indigo); border-color: var(--indigo); }

.notice {
  margin: 30px 0 0;
  padding: 12px 14px;
  border: 1px dashed var(--line);
  border-radius: var(--radius);
  font-family: var(--sans);
  font-size: 12px;
  line-height: 1.7;
  color: var(--ink-dim);
}

/* ---------- 劃記（annotation） ---------- */

.ch-nav .annotate-toggle {
  flex: none;
  padding: 5px 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  color: var(--indigo);
  font-family: var(--sans);
  font-size: 13px;
}

.ch-nav .annotate-toggle.active {
  background: var(--indigo);
  border-color: var(--indigo);
  color: #FFF;
}

.annotation-toolbar {
  position: sticky;
  top: 102px;
  z-index: 9;
  display: flex;
  gap: 6px;
  align-items: center;
  margin: -18px -22px 16px;
  padding: 8px 22px;
  overflow-x: auto;
  background: color-mix(in srgb, var(--paper) 94%, transparent);
  backdrop-filter: blur(10px);
  border-bottom: 1px solid var(--line);
}

.annotation-toolbar[hidden] { display: none; }

.annotation-tool,
.annotation-action {
  flex: none;
  min-width: 52px;
  min-height: 34px;
  padding: 6px 10px;
  border: 1px solid var(--line);
  border-radius: 6px;
  background: var(--surface);
  color: var(--ink);
  font-family: var(--sans);
  font-size: 13px;
}

.annotation-tool.selected {
  background: var(--indigo-soft);
  border-color: var(--indigo);
  color: var(--indigo);
  font-weight: 700;
}

.annotation-action { color: var(--ink-dim); }
.annotation-action:hover { border-color: var(--indigo); color: var(--indigo); }
.annotation-action:disabled { opacity: .4; cursor: default; }

body.annotation-active { overscroll-behavior: contain; }
body.annotation-active section.ch-section {
  user-select: none;
  -webkit-user-select: none;
}

section.ch-section.annotatable { position: relative; }
section.ch-section.annotatable > :not(.annotation-canvas) { position: relative; z-index: 1; }
section.ch-section .annotation-canvas {
  position: absolute;
  inset: 0;
  z-index: 2;
  width: 100%;
  height: 100%;
  pointer-events: none;
}

section.ch-section.annotating .annotation-canvas {
  pointer-events: auto;
  touch-action: none;
  cursor: crosshair;
}

/* ---------- 窄螢幕 ---------- */

@media (max-width: 560px) {
  body { font-size: 16.5px; }
  .view { padding: 20px 16px 64px; }
  .topbar { padding: 0 16px; }
  .brand-text small { display: none; }
  .ch-nav { margin: -20px -16px 16px; padding: 0 16px; }
  .annotation-toolbar { margin: -16px -16px 14px; padding: 8px 16px; }
  .sitefoot { padding: 18px 16px 40px; }
  .toc-item { grid-template-columns: 1.9rem 1fr; }
  .toc-state { grid-column: 2; }
  .resume-card { flex-direction: column; align-items: flex-start; }
}

@media (prefers-reduced-motion: reduce) {
  * { animation-duration: .01ms !important; transition-duration: .01ms !important; }
}