/* ===== MARL Communication Notes - Unified Styles ===== */

/* ---------- Reset & Base ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

:root {
  --bg: #fafaf9;
  --bg-sidebar: #1e293b;
  --bg-sidebar-hover: #334155;
  --bg-card: #ffffff;
  --text: #1e293b;
  --text-light: #64748b;
  --text-sidebar: #cbd5e1;
  --text-sidebar-active: #f8fafc;
  --accent: #2563eb;
  --accent-light: #dbeafe;
  --accent-dark: #1d4ed8;
  --border: #e2e8f0;
  --green: #16a34a;
  --green-light: #dcfce7;
  --orange: #ea580c;
  --orange-light: #ffedd5;
  --purple: #7c3aed;
  --purple-light: #ede9fe;
  --red: #dc2626;
  --red-light: #fee2e2;
  --radius: 8px;
  --shadow-sm: 0 1px 2px rgba(0,0,0,.05);
  --shadow: 0 1px 3px rgba(0,0,0,.1), 0 1px 2px rgba(0,0,0,.06);
  --shadow-lg: 0 4px 12px rgba(0,0,0,.1);
  --sidebar-w: 280px;
  --progress-h: 3px;
  --font-sans: "Segoe UI", "PingFang SC", "Microsoft YaHei", system-ui, -apple-system, sans-serif;
  --font-mono: "Cascadia Code", "Fira Code", "JetBrains Mono", Consolas, monospace;
}

html { scroll-behavior: smooth; font-size: 16px; }
body {
  font-family: var(--font-sans);
  color: var(--text);
  background: var(--bg);
  line-height: 1.75;
  display: flex;
  min-height: 100vh;
}

/* ---------- Progress Bar (top) ---------- */
#progress-bar {
  position: fixed;
  top: 0; left: 0;
  width: 0%;
  height: var(--progress-h);
  background: linear-gradient(90deg, var(--accent), var(--purple));
  z-index: 1000;
  transition: width .15s ease-out;
}

/* ---------- Sidebar ---------- */
#sidebar {
  position: fixed;
  top: 0; left: 0;
  width: var(--sidebar-w);
  height: 100vh;
  background: var(--bg-sidebar);
  color: var(--text-sidebar);
  display: flex;
  flex-direction: column;
  z-index: 900;
  overflow: hidden;
  transition: transform .3s ease;
}
#sidebar .sidebar-header {
  padding: 20px 18px 12px;
  border-bottom: 1px solid rgba(255,255,255,.08);
}
#sidebar .sidebar-header h2 {
  font-size: .85rem;
  text-transform: uppercase;
  letter-spacing: .08em;
  color: var(--text-sidebar);
  margin-bottom: 10px;
  font-weight: 600;
}
#sidebar .sidebar-header a {
  color: var(--text-sidebar);
  text-decoration: none;
  display: flex;
  align-items: center;
  gap: 6px;
  font-size: .95rem;
  margin-bottom: 10px;
  opacity: .85;
  transition: opacity .2s;
}
#sidebar .sidebar-header a:hover { opacity: 1; }
#search-box {
  width: 100%;
  padding: 8px 12px;
  border: 1px solid rgba(255,255,255,.15);
  border-radius: 6px;
  background: rgba(255,255,255,.06);
  color: #fff;
  font-size: .85rem;
  outline: none;
  transition: border-color .2s;
}
#search-box::placeholder { color: rgba(255,255,255,.35); }
#search-box:focus { border-color: var(--accent); }

#sidebar nav {
  flex: 1;
  overflow-y: auto;
  padding: 10px 0;
}
#sidebar nav::-webkit-scrollbar { width: 4px; }
#sidebar nav::-webkit-scrollbar-thumb { background: rgba(255,255,255,.12); border-radius: 2px; }

#sidebar nav ul { list-style: none; }
#sidebar nav > ul > li {}
#sidebar nav .nav-section-title {
  display: block;
  padding: 8px 18px 4px;
  font-size: .7rem;
  text-transform: uppercase;
  letter-spacing: .06em;
  color: rgba(255,255,255,.35);
  font-weight: 600;
}
#sidebar nav a {
  display: block;
  padding: 6px 18px 6px 24px;
  color: var(--text-sidebar);
  text-decoration: none;
  font-size: .85rem;
  border-left: 3px solid transparent;
  transition: all .15s;
}
#sidebar nav a:hover {
  background: var(--bg-sidebar-hover);
  color: var(--text-sidebar-active);
}
#sidebar nav a.active {
  background: rgba(37, 99, 235, .15);
  color: var(--text-sidebar-active);
  border-left-color: var(--accent);
  font-weight: 500;
}
#sidebar nav a.sub {
  padding-left: 40px;
  font-size: .8rem;
}
.nav-hidden { display: none !important; }

/* Mobile toggle */
#sidebar-toggle {
  display: none;
  position: fixed;
  top: 10px; left: 10px;
  z-index: 950;
  width: 40px; height: 40px;
  border: none;
  border-radius: 8px;
  background: var(--bg-sidebar);
  color: #fff;
  font-size: 1.2rem;
  cursor: pointer;
}

/* ---------- Main Content ---------- */
#main {
  margin-left: var(--sidebar-w);
  flex: 1;
  min-height: 100vh;
  padding: 40px 48px 80px;
  max-width: 900px;
}

/* ---------- Typography ---------- */
h1 {
  font-size: 1.85rem;
  font-weight: 700;
  margin-bottom: 8px;
  color: var(--text);
  line-height: 1.3;
}
.page-subtitle {
  font-size: 1rem;
  color: var(--text-light);
  margin-bottom: 28px;
  border-bottom: 1px solid var(--border);
  padding-bottom: 16px;
}
h2 {
  font-size: 1.35rem;
  font-weight: 650;
  margin: 36px 0 12px;
  padding-bottom: 6px;
  border-bottom: 2px solid var(--accent-light);
  color: var(--text);
}
h3 {
  font-size: 1.1rem;
  font-weight: 600;
  margin: 24px 0 8px;
  color: var(--accent-dark);
}
p { margin: 8px 0; }
a { color: var(--accent); }
a:hover { text-decoration: underline; }
strong { font-weight: 600; }
code {
  background: #f1f5f9;
  padding: 2px 6px;
  border-radius: 4px;
  font-family: var(--font-mono);
  font-size: .85em;
  color: var(--purple);
}

ul, ol { margin: 8px 0 8px 24px; }
li { margin: 4px 0; }

/* ---------- Cards / Concept Blocks ---------- */
.concept-block {
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  padding: 20px 24px;
  margin: 16px 0;
  box-shadow: var(--shadow-sm);
}
.concept-block summary {
  font-weight: 600;
  font-size: 1.05rem;
  cursor: pointer;
  padding: 4px 0;
  list-style: none;
  display: flex;
  align-items: center;
  gap: 8px;
}
.concept-block summary::before {
  content: "▸";
  font-size: .85rem;
  color: var(--accent);
  transition: transform .2s;
  display: inline-block;
}
.concept-block[open] summary::before {
  transform: rotate(90deg);
}
.concept-block summary::-webkit-details-marker { display: none; }
.concept-block .block-content {
  margin-top: 12px;
  padding-top: 12px;
  border-top: 1px solid var(--border);
}

/* Tag badges */
.tag {
  display: inline-block;
  padding: 2px 8px;
  border-radius: 12px;
  font-size: .7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-right: 4px;
}
.tag-info { background: var(--accent-light); color: var(--accent-dark); }
.tag-analogy { background: var(--green-light); color: var(--green); }
.tag-example { background: var(--orange-light); color: var(--orange); }
.tag-key { background: var(--purple-light); color: var(--purple); }
.tag-warning { background: var(--red-light); color: var(--red); }

/* Analogy & Example boxes */
.analogy-box, .example-box {
  border-radius: var(--radius);
  padding: 14px 18px;
  margin: 12px 0;
  font-size: .92rem;
}
.analogy-box {
  background: var(--green-light);
  border-left: 4px solid var(--green);
}
.analogy-box::before {
  content: "🏠 生活类比";
  display: block;
  font-weight: 600;
  font-size: .78rem;
  color: var(--green);
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-bottom: 6px;
}
.example-box {
  background: var(--orange-light);
  border-left: 4px solid var(--orange);
}
.example-box::before {
  content: "🤖 双智能体例子";
  display: block;
  font-weight: 600;
  font-size: .78rem;
  color: var(--orange);
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-bottom: 6px;
}

/* Key insight */
.key-insight {
  background: var(--purple-light);
  border-left: 4px solid var(--purple);
  border-radius: var(--radius);
  padding: 14px 18px;
  margin: 12px 0;
  font-size: .92rem;
}
.key-insight::before {
  content: "💡 核心洞察";
  display: block;
  font-weight: 600;
  font-size: .78rem;
  color: var(--purple);
  text-transform: uppercase;
  letter-spacing: .04em;
  margin-bottom: 6px;
}

/* ---------- Quiz / Self-test ---------- */
.quiz-section {
  background: #f0f9ff;
  border: 1px solid #bae6fd;
  border-radius: var(--radius);
  padding: 18px 22px;
  margin: 24px 0 12px;
}
.quiz-section h3 {
  color: var(--accent);
  margin: 0 0 12px;
  font-size: 1rem;
}
.quiz-item {
  margin: 10px 0;
}
.quiz-item .quiz-q {
  font-weight: 600;
  font-size: .9rem;
  cursor: default;
}
.quiz-item .quiz-a {
  display: none;
  margin-top: 8px;
  padding: 10px 14px;
  background: #fff;
  border-radius: 6px;
  border: 1px solid var(--border);
  font-size: .88rem;
  color: var(--text);
}
.quiz-item .quiz-a.show { display: block; }
.quiz-toggle-btn {
  margin-top: 6px;
  padding: 4px 14px;
  border: 1px solid var(--accent);
  border-radius: 6px;
  background: transparent;
  color: var(--accent);
  font-size: .8rem;
  cursor: pointer;
  transition: all .15s;
}
.quiz-toggle-btn:hover {
  background: var(--accent);
  color: #fff;
}

/* ---------- SVG Diagrams ---------- */
.svg-container {
  margin: 16px 0;
  text-align: center;
  overflow-x: auto;
}
.svg-container svg {
  max-width: 100%;
  height: auto;
}

/* ---------- Tooltip ---------- */
.term-tooltip {
  position: relative;
  border-bottom: 1px dashed var(--accent);
  cursor: help;
  color: var(--accent-dark);
  font-weight: 500;
}
.term-tooltip .tooltip-text {
  visibility: hidden;
  opacity: 0;
  position: absolute;
  bottom: calc(100% + 8px);
  left: 50%;
  transform: translateX(-50%);
  width: max-content;
  max-width: 280px;
  padding: 8px 12px;
  background: var(--bg-sidebar);
  color: #f1f5f9;
  font-size: .8rem;
  font-weight: 400;
  border-radius: 6px;
  box-shadow: var(--shadow-lg);
  z-index: 100;
  pointer-events: none;
  transition: opacity .2s, visibility .2s;
  line-height: 1.5;
  text-align: left;
}
.term-tooltip .tooltip-text::after {
  content: "";
  position: absolute;
  top: 100%;
  left: 50%;
  transform: translateX(-50%);
  border: 6px solid transparent;
  border-top-color: var(--bg-sidebar);
}
.term-tooltip:hover .tooltip-text {
  visibility: visible;
  opacity: 1;
}

/* ---------- Page Navigation ---------- */
.page-nav {
  display: flex;
  justify-content: space-between;
  margin-top: 48px;
  padding-top: 20px;
  border-top: 1px solid var(--border);
  gap: 16px;
}
.page-nav a {
  display: flex;
  align-items: center;
  gap: 6px;
  padding: 10px 18px;
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  font-size: .9rem;
  color: var(--text);
  background: var(--bg-card);
  transition: all .15s;
}
.page-nav a:hover {
  border-color: var(--accent);
  color: var(--accent);
  box-shadow: var(--shadow);
}
.page-nav .prev::before { content: "← "; }
.page-nav .next::after { content: " →"; }

/* ---------- Index Page Cards ---------- */
.chapter-grid {
  display: grid;
  grid-template-columns: 1fr;
  gap: 14px;
  margin: 20px 0;
}
.chapter-card {
  display: flex;
  align-items: flex-start;
  gap: 14px;
  padding: 18px 20px;
  background: var(--bg-card);
  border: 1px solid var(--border);
  border-radius: var(--radius);
  text-decoration: none;
  color: var(--text);
  transition: all .2s;
  box-shadow: var(--shadow-sm);
}
.chapter-card:hover {
  border-color: var(--accent);
  box-shadow: var(--shadow);
  transform: translateY(-1px);
  text-decoration: none;
}
.chapter-card .card-num {
  display: flex;
  align-items: center;
  justify-content: center;
  width: 36px;
  height: 36px;
  border-radius: 50%;
  background: var(--accent-light);
  color: var(--accent-dark);
  font-weight: 700;
  font-size: .9rem;
  flex-shrink: 0;
}
.chapter-card .card-body h3 {
  margin: 0 0 4px;
  font-size: 1rem;
  color: var(--text);
}
.chapter-card .card-body p {
  font-size: .85rem;
  color: var(--text-light);
  margin: 0;
}

/* Overview hero */
.hero-summary {
  background: linear-gradient(135deg, var(--accent-light), var(--purple-light));
  border-radius: var(--radius);
  padding: 24px 28px;
  margin-bottom: 28px;
}
.hero-summary p {
  font-size: .95rem;
  line-height: 1.8;
}

/* ---------- Search Highlight ---------- */
.search-highlight {
  background: #fef08a;
  padding: 1px 2px;
  border-radius: 2px;
}

/* ---------- Responsive ---------- */
@media (max-width: 860px) {
  #sidebar {
    transform: translateX(-100%);
  }
  #sidebar.open {
    transform: translateX(0);
  }
  #sidebar-toggle {
    display: block;
  }
  #main {
    margin-left: 0;
    padding: 24px 20px 60px;
  }
}
@media (min-width: 1200px) {
  #main {
    padding-left: 64px;
    padding-right: 64px;
  }
}

/* ---------- Print ---------- */
@media print {
  #sidebar, #progress-bar, #sidebar-toggle { display: none; }
  #main { margin-left: 0; max-width: 100%; }
  .quiz-item .quiz-a { display: block !important; }
}