/* ============================================================
   Brook Trading Lab — Local Fonts (替代 Google Fonts)
   ============================================================ */

@font-face {
  font-family: 'Inter';
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/Inter-Regular.woff2') format('woff2');
}

@font-face {
  font-family: 'Inter';
  font-weight: 500;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/Inter-Medium.woff2') format('woff2');
}

@font-face {
  font-family: 'Inter';
  font-weight: 600;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/Inter-SemiBold.woff2') format('woff2');
}

@font-face {
  font-family: 'Inter';
  font-weight: 700;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/Inter-Bold.woff2') format('woff2');
}

@font-face {
  font-family: 'Inter';
  font-weight: 800;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/Inter-ExtraBold.woff2') format('woff2');
}

@font-face {
  font-family: 'JetBrains Mono';
  font-weight: 400;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/JetBrainsMono-Regular.woff2') format('woff2');
}

@font-face {
  font-family: 'JetBrains Mono';
  font-weight: 500;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/JetBrainsMono-Medium.woff2') format('woff2');
}

@font-face {
  font-family: 'JetBrains Mono';
  font-weight: 600;
  font-style: normal;
  font-display: swap;
  src: url('/fonts/JetBrainsMono-SemiBold.woff2') format('woff2');
}

/* ============================================================
   Brook Trading Lab — Design System (v2)
   Modern Knowledge Card Style
   Brand: Indigo-600 (#4F46E5) -> Violet-500 (#8B5CF6)
   ============================================================ */

/* ---------- CSS Custom Properties ---------- */
:root {
  --c-bg:          #FFFFFF;
  --c-bg-alt:      #F9FAFB;
  --c-bg-code:     #F1F5F9;
  --c-primary:     #4F46E5;
  --c-primary-mid: #6366F1;
  --c-primary-lt:  #818CF8;
  --c-accent:      #8B5CF6;
  --c-highlight:   #0EA5E9;
  --c-success:     #10B981;
  --c-warning:     #F59E0B;
  --c-danger:      #F43F5E;
  --c-text:        #111827;
  --c-text-body:   #374151;
  --c-text-muted:  #6B7280;
  --c-link:        #4F46E5;
  --c-link-hover:  #3730A3;
  --c-border:      #E5E7EB;
  --c-white:       #FFFFFF;
  --gradient-brand: linear-gradient(135deg, #4F46E5, #8B5CF6);
  --gradient-hero:  linear-gradient(135deg, #4F46E5 0%, #8B5CF6 100%);
  --gradient-card:  linear-gradient(135deg, rgba(79,70,229,0.05), rgba(139,92,246,0.05));
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
  --font-mono: 'JetBrains Mono', 'Fira Code', 'Consolas', monospace;
  --text-hero:    48px;
  --text-h1:      36px;
  --text-h2:      28px;
  --text-h3:      22px;
  --text-body:    16px;
  --text-sm:      14px;
  --text-xs:      12px;
  --text-code:    14px;
  --space-xs:   4px;
  --space-sm:   8px;
  --space-md:   16px;
  --space-lg:   24px;
  --space-xl:   32px;
  --space-2xl:  48px;
  --space-3xl:  64px;
  --space-4xl:  96px;
  --max-w:        1200px;
  --max-w-article: 780px;
  --nav-h:        64px;
  --radius-sm:    8px;
  --radius-md:    12px;
  --radius-lg:    16px;
  --radius-full:  9999px;
  --shadow-sm:  0 1px 2px rgba(0,0,0,0.05);
  --shadow-md:  0 4px 6px -1px rgba(0,0,0,0.07), 0 2px 4px -2px rgba(0,0,0,0.05);
  --shadow-lg:  0 10px 15px -3px rgba(0,0,0,0.08), 0 4px 6px -4px rgba(0,0,0,0.04);
  --shadow-xl:  0 20px 25px -5px rgba(0,0,0,0.08), 0 8px 10px -6px rgba(0,0,0,0.04);
  --transition-fast: 150ms ease;
  --transition-base: 200ms ease;
  --transition-slow: 300ms ease;
}

/* ---------- Reset & Base ---------- */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; -webkit-text-size-adjust: 100%; scroll-padding-top: var(--nav-h); }
body {
  font-family: var(--font-main);
  font-size: var(--text-body);
  line-height: 1.7;
  color: var(--c-text-body);
  background: var(--c-bg);
  -webkit-font-smoothing: antialiased;
  -moz-osx-font-smoothing: grayscale;
}
a { color: var(--c-link); text-decoration: none; transition: color var(--transition-fast); }
a:hover { color: var(--c-link-hover); }
img { max-width: 100%; height: auto; }

/* ---------- Typography ---------- */
h1, h2, h3, h4, h5, h6 { color: var(--c-text); font-weight: 700; line-height: 1.25; }
h1 { font-size: var(--text-h1); }
h2 { font-size: var(--text-h2); }
h3 { font-size: var(--text-h3); }
h1.hero-title { font-size: var(--text-hero); line-height: 1.15; }
p { margin-bottom: var(--space-md); }
small { font-size: var(--text-sm); }

/* ---------- Utilities ---------- */
.container { width: 100%; max-width: var(--max-w); margin: 0 auto; padding: 0 var(--space-lg); }
.text-center { text-align: center; }
.text-muted { color: var(--c-text-muted); }
.sr-only { position: absolute; width: 1px; height: 1px; padding: 0; margin: -1px; overflow: hidden; clip: rect(0,0,0,0); white-space: nowrap; border: 0; }

/* ---------- Buttons ---------- */
.btn {
  display: inline-flex; align-items: center; gap: var(--space-sm);
  padding: var(--space-sm) var(--space-lg);
  font-size: var(--text-body); font-weight: 600; font-family: var(--font-main);
  border: 2px solid transparent; border-radius: var(--radius-sm);
  cursor: pointer; transition: all var(--transition-base); text-decoration: none; line-height: 1.5;
}
.btn-primary { background: var(--c-primary); color: var(--c-white); border-color: var(--c-primary); }
.btn-primary:hover { background: var(--c-link-hover); border-color: var(--c-link-hover); color: var(--c-white); transform: translateY(-1px); box-shadow: var(--shadow-md); }
.btn-outline { background: transparent; color: var(--c-primary); border-color: var(--c-primary); }
.btn-outline:hover { background: var(--c-primary); color: var(--c-white); transform: translateY(-1px); }
.btn-white { background: var(--c-white); color: var(--c-primary); border-color: var(--c-white); }
.btn-white:hover { background: rgba(255,255,255,0.9); color: var(--c-link-hover); transform: translateY(-1px); }
.btn-sm { padding: var(--space-xs) var(--space-md); font-size: var(--text-sm); }

/* ---------- Navigation ---------- */
.navbar {
  position: sticky; top: 0; z-index: 100; height: var(--nav-h);
  background: rgba(255,255,255,0.92); backdrop-filter: blur(12px);
  -webkit-backdrop-filter: blur(12px);
  border-bottom: 1px solid var(--c-border);
  display: flex; align-items: center; transition: box-shadow var(--transition-base);
}
.navbar.scrolled { box-shadow: var(--shadow-md); }
.navbar .container { display: flex; align-items: center; justify-content: space-between; height: 100%; }
.navbar-brand {
  display: flex; align-items: center; gap: var(--space-sm);
  font-size: var(--text-h3); font-weight: 700; color: var(--c-text); text-decoration: none;
}
.navbar-brand:hover { color: var(--c-primary); }
.navbar-brand svg { flex-shrink: 0; }
.navbar-links { display: flex; align-items: center; gap: var(--space-lg); list-style: none; }
.navbar-links a {
  font-size: var(--text-sm); font-weight: 500; color: var(--c-text-body);
  text-decoration: none; padding: var(--space-xs) 0; position: relative; transition: color var(--transition-fast);
}
.navbar-links a:hover, .navbar-links a.active { color: var(--c-primary); }
.navbar-links a.active::after {
  content: ''; position: absolute; bottom: -2px; left: 0; right: 0;
  height: 2px; background: var(--c-primary); border-radius: 1px;
}
.navbar-toggle {
  display: none; background: none; border: none; cursor: pointer;
  padding: var(--space-sm); color: var(--c-text);
}
.navbar-toggle svg { display: block; }

/* ---------- Hero ---------- */
.hero {
  background: var(--gradient-hero); color: var(--c-white);
  padding: var(--space-4xl) 0 var(--space-3xl); text-align: center;
  position: relative; overflow: hidden;
}
.hero-inner { position: relative; z-index: 2; }
.hero .hero-title { font-size: var(--text-hero); color: var(--c-white); margin-bottom: var(--space-md); }
.hero .hero-subtitle { font-size: var(--text-h3); color: rgba(255,255,255,0.85); max-width: 600px; margin: 0 auto var(--space-xl); }
.hero-cta { display: flex; gap: var(--space-md); justify-content: center; flex-wrap: wrap; }
.hero-decoration { position: absolute; bottom: 0; left: 0; right: 0; opacity: 0.15; z-index: 1; }

/* ---------- Stats Bar ---------- */
.stats-bar { background: var(--c-bg-alt); border-top: 1px solid var(--c-border); border-bottom: 1px solid var(--c-border); padding: var(--space-xl) 0; }
.stats-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-lg); text-align: center; }
.stat-item { padding: var(--space-md); }
.stat-number { font-size: var(--text-h1); font-weight: 800; background: var(--gradient-brand); -webkit-background-clip: text; -webkit-text-fill-color: transparent; background-clip: text; }
.stat-label { font-size: var(--text-sm); color: var(--c-text-muted); margin-top: var(--space-xs); }

/* ---------- Section ---------- */
.section { padding: var(--space-3xl) 0; }
.section-alt { background: var(--c-bg-alt); }
.section-title { font-size: var(--text-h2); text-align: center; margin-bottom: var(--space-xs); }
.section-desc { text-align: center; color: var(--c-text-muted); margin-bottom: var(--space-2xl); max-width: 600px; margin-left: auto; margin-right: auto; }

/* ---------- Domain Cards ---------- */
.domain-grid { display: grid; grid-template-columns: repeat(3, 1fr); gap: var(--space-lg); }
.domain-card {
  background: var(--c-white); border: 1px solid var(--c-border);
  border-radius: var(--radius-md); padding: var(--space-xl);
  transition: transform var(--transition-base), box-shadow var(--transition-base), border-color var(--transition-base);
  cursor: pointer; text-decoration: none; color: inherit;
  display: flex; flex-direction: column; position: relative; overflow: hidden;
}
.domain-card::before {
  content: ''; position: absolute; top: 0; left: 0; right: 0;
  height: 3px; background: var(--gradient-brand); transform: scaleX(0);
  transform-origin: left; transition: transform var(--transition-base);
}
.domain-card:hover { transform: translateY(-2px); box-shadow: var(--shadow-lg); border-color: var(--c-primary-lt); }
.domain-card:hover::before { transform: scaleX(1); }
.domain-card-icon {
  width: 48px; height: 48px; border-radius: var(--radius-sm);
  background: var(--gradient-card); display: flex; align-items: center;
  justify-content: center; margin-bottom: var(--space-md); color: var(--c-primary);
}
.domain-card-icon svg { width: 24px; height: 24px; }
.domain-card-name { font-size: var(--text-h3); font-weight: 700; color: var(--c-text); margin-bottom: var(--space-sm); }
.domain-card-desc { font-size: var(--text-sm); color: var(--c-text-muted); flex: 1; line-height: 1.6; }
.domain-card-footer { display: flex; align-items: center; justify-content: space-between; margin-top: var(--space-md); padding-top: var(--space-md); border-top: 1px solid var(--c-border); }
.domain-card-count { font-size: var(--text-xs); font-weight: 600; color: var(--c-primary); background: rgba(79,70,229,0.08); padding: 2px 10px; border-radius: var(--radius-full); }

/* ---------- Learning Path Timeline ---------- */
.path-timeline { display: flex; gap: 0; position: relative; justify-content: center; }
.path-timeline::before {
  content: ''; position: absolute; top: 28px; left: 15%; right: 15%;
  height: 3px; background: var(--c-border); border-radius: 2px; z-index: 0;
}
.path-phase { flex: 1; max-width: 360px; text-align: center; position: relative; z-index: 1; padding: 0 var(--space-md); }
.path-phase-number {
  width: 56px; height: 56px; border-radius: 50%;
  background: var(--gradient-brand); color: var(--c-white);
  font-size: var(--text-h2); font-weight: 800;
  display: flex; align-items: center; justify-content: center;
  margin: 0 auto var(--space-md); box-shadow: var(--shadow-md);
}
.path-phase-name { font-size: var(--text-h3); font-weight: 700; color: var(--c-text); margin-bottom: var(--space-xs); }
.path-phase-desc { font-size: var(--text-sm); color: var(--c-text-muted); margin-bottom: var(--space-md); }
.path-domains { display: flex; flex-wrap: wrap; gap: var(--space-sm); justify-content: center; }
.path-domain-tag {
  font-size: var(--text-xs); font-weight: 500; padding: 4px 12px;
  border-radius: var(--radius-full); background: var(--c-bg-alt);
  color: var(--c-text-body); border: 1px solid var(--c-border);
  transition: all var(--transition-fast);
}
.path-domain-tag:hover { background: var(--c-primary); color: var(--c-white); border-color: var(--c-primary); }

/* ---------- Breadcrumb ---------- */
.breadcrumb { display: flex; align-items: center; gap: var(--space-sm); font-size: var(--text-sm); color: var(--c-text-muted); padding: var(--space-lg) 0; flex-wrap: wrap; }
.breadcrumb a { color: var(--c-primary); }
.breadcrumb a:hover { text-decoration: underline; }
.breadcrumb-sep { color: var(--c-text-muted); }

/* ---------- Domain Header ---------- */
.domain-header { display: flex; gap: var(--space-lg); align-items: flex-start; margin-bottom: var(--space-2xl); }
.domain-header-icon {
  width: 72px; height: 72px; border-radius: var(--radius-md);
  background: var(--gradient-card); display: flex; align-items: center;
  justify-content: center; flex-shrink: 0; color: var(--c-primary);
}
.domain-header-icon svg { width: 36px; height: 36px; }
.domain-header-info h1 { margin-bottom: var(--space-sm); }
.domain-header-info p { color: var(--c-text-muted); max-width: 640px; }

/* ---------- Article List ---------- */
.article-list { display: flex; flex-direction: column; }
.article-list-item {
  display: flex; align-items: center; gap: var(--space-md);
  padding: var(--space-lg); border: 1px solid var(--c-border);
  border-radius: var(--radius-md); margin-bottom: var(--space-md);
  text-decoration: none; color: inherit; transition: all var(--transition-base);
  background: var(--c-white);
}
.article-list-item:hover { border-color: var(--c-primary-lt); box-shadow: var(--shadow-md); transform: translateY(-1px); }
.article-difficulty {
  font-size: var(--text-xs); font-weight: 600; padding: 2px 10px;
  border-radius: var(--radius-full); white-space: nowrap; flex-shrink: 0;
}
.difficulty-beginner { background: rgba(16,185,129,0.1); color: var(--c-success); }
.difficulty-intermediate { background: rgba(245,158,11,0.1); color: var(--c-warning); }
.difficulty-advanced { background: rgba(244,63,94,0.1); color: var(--c-danger); }
.article-list-body { flex: 1; min-width: 0; }
.article-list-title { font-size: var(--text-body); font-weight: 600; color: var(--c-text); margin-bottom: 2px; }
.article-list-item:hover .article-list-title { color: var(--c-primary); }
.article-list-summary {
  font-size: var(--text-sm); color: var(--c-text-muted);
  display: -webkit-box; -webkit-line-clamp: 2; -webkit-box-orient: vertical; overflow: hidden;
}
.article-list-meta { display: flex; align-items: center; gap: var(--space-md); font-size: var(--text-xs); color: var(--c-text-muted); flex-shrink: 0; }
.article-list-arrow { color: var(--c-text-muted); transition: transform var(--transition-fast), color var(--transition-fast); }
.article-list-item:hover .article-list-arrow { color: var(--c-primary); transform: translateX(3px); }

/* ---------- Sidebar ---------- */
.content-layout { display: grid; grid-template-columns: 1fr 280px; gap: var(--space-2xl); align-items: start; }
.sidebar-nav {
  position: sticky; top: calc(var(--nav-h) + var(--space-lg));
  background: var(--c-bg-alt); border: 1px solid var(--c-border);
  border-radius: var(--radius-md); padding: var(--space-lg);
}
.sidebar-nav-title {
  font-size: var(--text-sm); font-weight: 700; color: var(--c-text);
  text-transform: uppercase; letter-spacing: 0.05em;
  margin-bottom: var(--space-md); padding-bottom: var(--space-sm);
  border-bottom: 1px solid var(--c-border);
}
.sidebar-nav-list { list-style: none; }
.sidebar-nav-list li { margin-bottom: var(--space-xs); }
.sidebar-nav-list a {
  display: block; font-size: var(--text-sm); color: var(--c-text-muted);
  padding: var(--space-xs) var(--space-sm); border-radius: var(--radius-sm);
  transition: all var(--transition-fast); text-decoration: none;
}
.sidebar-nav-list a:hover, .sidebar-nav-list a.active { color: var(--c-primary); background: rgba(79,70,229,0.06); }

/* ---------- Article Page ---------- */
.article-progress-bar {
  position: fixed; top: var(--nav-h); left: 0; right: 0;
  height: 3px; background: var(--c-bg-alt); z-index: 99;
}
.article-progress-fill { height: 100%; background: var(--gradient-brand); width: 0%; transition: width 100ms linear; border-radius: 0 2px 2px 0; }
.article-hero {
  background: var(--gradient-card); border-bottom: 1px solid var(--c-border);
  padding: var(--space-2xl) 0; margin-bottom: var(--space-2xl);
}
.article-hero h1 { font-size: var(--text-h1); margin-bottom: var(--space-md); }
.article-meta { display: flex; flex-wrap: wrap; gap: var(--space-md); font-size: var(--text-sm); color: var(--c-text-muted); }
.article-meta-item { display: flex; align-items: center; gap: var(--space-xs); }
.article-meta-item svg { width: 16px; height: 16px; }

/* TOC */
.toc-panel { position: sticky; top: calc(var(--nav-h) + var(--space-lg)); }
.toc-title { font-size: var(--text-sm); font-weight: 700; color: var(--c-text); margin-bottom: var(--space-md); }
.toc-list { list-style: none; font-size: var(--text-sm); }
.toc-list li { margin-bottom: var(--space-xs); }
.toc-list a {
  display: block; color: var(--c-text-muted); text-decoration: none;
  padding: 3px var(--space-sm); border-left: 2px solid var(--c-border);
  transition: all var(--transition-fast);
}
.toc-list a:hover, .toc-list a.active { color: var(--c-primary); border-left-color: var(--c-primary); }

/* Article Content */
.article-content { max-width: 100%; }
.article-content h2 { margin-top: var(--space-2xl); margin-bottom: var(--space-md); padding-bottom: var(--space-sm); border-bottom: 1px solid var(--c-border); }
.article-content h3 { margin-top: var(--space-xl); margin-bottom: var(--space-sm); }
.article-content p { margin-bottom: var(--space-md); }
.article-content ul, .article-content ol { margin-bottom: var(--space-md); padding-left: var(--space-xl); }
.article-content li { margin-bottom: var(--space-xs); }
.article-content pre { background: var(--c-bg-code); border: 1px solid var(--c-border); border-radius: var(--radius-sm); padding: var(--space-lg); overflow-x: auto; margin-bottom: var(--space-md); }
.article-content code { font-family: var(--font-mono); font-size: var(--text-code); }
.article-content pre code { background: none; padding: 0; }
.article-content blockquote { border-left: 4px solid var(--c-primary); background: rgba(79,70,229,0.04); padding: var(--space-md) var(--space-lg); margin-bottom: var(--space-md); border-radius: 0 var(--radius-sm) var(--radius-sm) 0; color: var(--c-text-body); }
.article-content table { width: 100%; border-collapse: collapse; margin-bottom: var(--space-md); font-size: var(--text-sm); }
.article-content th, .article-content td { padding: var(--space-sm) var(--space-md); border: 1px solid var(--c-border); text-align: left; }
.article-content th { background: var(--c-bg-alt); font-weight: 600; color: var(--c-text); }
.article-content tr:nth-child(even) { background: var(--c-bg-alt); }

/* Prev/Next nav */
.article-nav { display: grid; grid-template-columns: 1fr 1fr; gap: var(--space-lg); margin-top: var(--space-2xl); padding-top: var(--space-xl); border-top: 1px solid var(--c-border); }
.article-nav a {
  display: flex; flex-direction: column; gap: var(--space-xs);
  padding: var(--space-lg); border: 1px solid var(--c-border);
  border-radius: var(--radius-md); text-decoration: none; color: inherit;
  transition: all var(--transition-base);
}
.article-nav a:hover { border-color: var(--c-primary-lt); box-shadow: var(--shadow-md); }
.article-nav a:hover .article-nav-title { color: var(--c-primary); }
.article-nav-label { font-size: var(--text-xs); color: var(--c-text-muted); }
.article-nav-title { font-size: var(--text-sm); font-weight: 600; color: var(--c-text); transition: color var(--transition-fast); }
.article-nav-next { text-align: right; }

/* ---------- Footer ---------- */
.footer { background: var(--c-bg-alt); border-top: 1px solid var(--c-border); padding: var(--space-3xl) 0 0; }
.footer-grid { display: grid; grid-template-columns: 2fr 1fr 1fr 1fr; gap: var(--space-2xl); margin-bottom: var(--space-2xl); }
.footer-col h4 { font-size: var(--text-sm); font-weight: 700; color: var(--c-text); text-transform: uppercase; letter-spacing: 0.05em; margin-bottom: var(--space-md); }
.footer-col p { font-size: var(--text-sm); color: var(--c-text-muted); line-height: 1.6; }
.footer-col ul { list-style: none; }
.footer-col li { margin-bottom: var(--space-sm); }
.footer-col a { font-size: var(--text-sm); color: var(--c-text-muted); text-decoration: none; transition: color var(--transition-fast); }
.footer-col a:hover { color: var(--c-primary); }
.footer-bottom { border-top: 1px solid var(--c-border); padding: var(--space-lg) 0; text-align: center; font-size: var(--text-sm); color: var(--c-text-muted); }

/* ---------- Loading ---------- */
.loading-skeleton { background: linear-gradient(90deg, var(--c-bg-alt) 25%, var(--c-border) 50%, var(--c-bg-alt) 75%); background-size: 200% 100%; animation: shimmer 1.5s infinite; border-radius: var(--radius-sm); }
@keyframes shimmer { 0% { background-position: 200% 0; } 100% { background-position: -200% 0; } }

/* ---------- Responsive ---------- */
@media (max-width: 1023px) {
  .domain-grid { grid-template-columns: repeat(2, 1fr); }
  .content-layout { grid-template-columns: 1fr 240px; gap: var(--space-lg); }
  .footer-grid { grid-template-columns: 1fr 1fr; }
}
@media (max-width: 767px) {
  :root { --nav-h: 56px; }
  h1 { font-size: 28px; }
  h1.hero-title { font-size: 32px; }
  h2 { font-size: 22px; }
  h3 { font-size: 18px; }
  .container { padding: 0 var(--space-md); }
  .hero { padding: var(--space-3xl) 0 var(--space-2xl); }
  .hero .hero-subtitle { font-size: var(--text-body); }
  .domain-grid { grid-template-columns: 1fr; }
  .stats-grid { grid-template-columns: 1fr; gap: var(--space-md); }
  .stat-item { display: flex; align-items: center; gap: var(--space-md); text-align: left; }
  .path-timeline { flex-direction: column; align-items: center; }
  .path-timeline::before { display: none; }
  .path-phase { max-width: 100%; }
  .content-layout { grid-template-columns: 1fr; }
  .toc-panel { position: relative; top: auto; margin-bottom: var(--space-lg); }
  .toc-toggle { display: none; }
  .toc-body { display: block !important; }
  .domain-header { flex-direction: column; gap: var(--space-md); }
  .domain-header-icon { width: 56px; height: 56px; }
  .domain-header-icon svg { width: 28px; height: 28px; }
  .article-list-item { flex-direction: column; align-items: flex-start; }
  .article-list-meta { width: 100%; justify-content: space-between; }
  .article-nav { grid-template-columns: 1fr; }
  .article-nav-next { text-align: left; }
  .footer-grid { grid-template-columns: 1fr; }
  .navbar-links { display: none; }
  .navbar-links.open {
    display: flex; flex-direction: column; position: absolute;
    top: var(--nav-h); left: 0; right: 0; background: var(--c-white);
    border-bottom: 1px solid var(--c-border); padding: var(--space-md);
    box-shadow: var(--shadow-lg); gap: var(--space-sm);
  }
  .navbar-toggle { display: block; }
}
@media print {
  .navbar, .article-progress-bar, .sidebar-nav, .toc-panel, .footer, .hero-decoration { display: none; }
  body { color: #000; background: #fff; }
  .container { max-width: 100%; }
}

/* ============================================================
   Phase 2: Dark Mode, Search, Bookmarks, PWA
   ============================================================ */

/* ---------- Dark Mode ---------- */
[data-theme="dark"] {
  --c-bg: #0F172A;
  --c-bg-alt: #1E293B;
  --c-bg-code: #1E293B;
  --c-text: #F1F5F9;
  --c-text-body: #CBD5E1;
  --c-text-muted: #94A3B8;
  --c-link: #818CF8;
  --c-link-hover: #A5B4FC;
  --c-border: #334155;
  --c-white: #1E293B;
  --gradient-card: linear-gradient(135deg, rgba(79,70,229,0.15), rgba(139,92,246,0.15));
  --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
  --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.4), 0 2px 4px -2px rgba(0,0,0,0.3);
  --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.4), 0 4px 6px -4px rgba(0,0,0,0.3);
  --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.4), 0 8px 10px -6px rgba(0,0,0,0.3);
}

/* System preference detection */
@media (prefers-color-scheme: dark) {
  [data-theme="system"] {
    --c-bg: #0F172A;
    --c-bg-alt: #1E293B;
    --c-bg-code: #1E293B;
    --c-text: #F1F5F9;
    --c-text-body: #CBD5E1;
    --c-text-muted: #94A3B8;
    --c-link: #818CF8;
    --c-link-hover: #A5B4FC;
    --c-border: #334155;
    --c-white: #1E293B;
    --gradient-card: linear-gradient(135deg, rgba(79,70,229,0.15), rgba(139,92,246,0.15));
    --shadow-sm: 0 1px 2px rgba(0,0,0,0.3);
    --shadow-md: 0 4px 6px -1px rgba(0,0,0,0.4), 0 2px 4px -2px rgba(0,0,0,0.3);
    --shadow-lg: 0 10px 15px -3px rgba(0,0,0,0.4), 0 4px 6px -4px rgba(0,0,0,0.3);
    --shadow-xl: 0 20px 25px -5px rgba(0,0,0,0.4), 0 8px 10px -6px rgba(0,0,0,0.3);
  }
}

/* Dark mode: navbar */
[data-theme="dark"] .navbar,
[data-theme="dark"] .navbar.scrolled {
  background: rgba(15,23,42,0.95) !important;
  border-bottom-color: #334155 !important;
}
@media (prefers-color-scheme: dark) {
  [data-theme="system"] .navbar,
  [data-theme="system"] .navbar.scrolled {
    background: rgba(15,23,42,0.95) !important;
    border-bottom-color: #334155 !important;
  }
}

/* Dark mode: card backgrounds */
[data-theme="dark"] .domain-card,
[data-theme="dark"] .article-list-item {
  background: #1E293B;
  border-color: #334155;
}
[data-theme="dark"] .article-list-item:hover {
  border-color: #6366F1;
}

/* Dark mode: footer */
[data-theme="dark"] .footer {
  background: #1E293B;
  border-top-color: #334155;
}
[data-theme="dark"] .footer-col h4 {
  color: #F1F5F9;
}

/* Dark mode: section-alt */
[data-theme="dark"] .section-alt,
[data-theme="dark"] .stats-bar {
  background: #1E293B;
  border-bottom-color: #334155;
  border-top-color: #334155;
}

/* Dark mode: sidebar */
[data-theme="dark"] .sidebar-nav {
  background: #1E293B;
  border-color: #334155;
}

/* Dark mode: hero decoration */
[data-theme="dark"] .hero-decoration {
  opacity: 0.08;
}

/* Dark mode: article hero */
[data-theme="dark"] .article-hero {
  background: var(--gradient-card);
  border-bottom-color: #334155;
}

/* Dark mode: article content */
[data-theme="dark"] .article-content h2 {
  border-bottom-color: #334155;
}
[data-theme="dark"] .article-content pre {
  background: #1E293B;
  border-color: #334155;
}
[data-theme="dark"] .article-content blockquote {
  background: rgba(79,70,229,0.15);
}
[data-theme="dark"] .article-content th {
  background: #1E293B;
}
[data-theme="dark"] .article-content tr:nth-child(even) {
  background: #1E293B;
}
[data-theme="dark"] .article-nav a {
  border-color: #334155;
}
[data-theme="dark"] .toc-panel {
  background: #1E293B;
  border-color: #334155;
}
[data-theme="dark"] .toc-panel .toc-title {
  color: #F1F5F9;
}
[data-theme="dark"] .toc-list a {
  color: #94A3B8;
  border-left-color: #334155;
}
[data-theme="dark"] .toc-list a:hover,
[data-theme="dark"] .toc-list a.active {
  color: #818CF8;
  border-left-color: #818CF8;
}

/* Dark mode: mobile menu */
@media (max-width: 767px) {
  [data-theme="dark"] .navbar-links.open {
    background: #1E293B;
    border-bottom-color: #334155;
  }
}

/* ---------- Theme Toggle Button ---------- */
.theme-toggle-btn {
  background: none; border: none; cursor: pointer;
  padding: var(--space-xs) var(--space-sm);
  color: var(--c-text); font-size: var(--text-sm);
  transition: color var(--transition-fast), transform var(--transition-fast);
  border-radius: var(--radius-sm);
  display: flex; align-items: center; gap: 4px;
  line-height: 1;
}
.theme-toggle-btn:hover {
  color: var(--c-primary);
  background: rgba(79,70,229,0.06);
}
.theme-toggle-btn .icon-sun { display: inline; }
.theme-toggle-btn .icon-moon { display: none; }
[data-theme="dark"] .theme-toggle-btn .icon-sun { display: none; }
[data-theme="dark"] .theme-toggle-btn .icon-moon { display: inline; }
@media (prefers-color-scheme: dark) {
  [data-theme="system"] .theme-toggle-btn .icon-sun { display: none; }
  [data-theme="system"] .theme-toggle-btn .icon-moon { display: inline; }
}

/* ---------- Search Button ---------- */
.navbar-search-btn {
  background: none; border: 1px solid var(--c-border); cursor: pointer;
  padding: 6px; color: var(--c-text-muted); border-radius: var(--radius-sm);
  transition: all var(--transition-fast); display: flex; align-items: center; justify-content: center;
}
.navbar-search-btn:hover {
  color: var(--c-primary); border-color: var(--c-primary-lt);
}
.navbar-search-btn kbd {
  font-size: 10px; padding: 1px 5px; border-radius: 3px;
  background: var(--c-bg-alt); color: var(--c-text-muted);
  border: 1px solid var(--c-border); margin-left: 6px; font-family: var(--font-mono);
}
@media (max-width: 767px) {
  .navbar-search-btn kbd { display: none; }
}

/* ---------- Search Panel (Spotlight) ---------- */
.search-overlay {
  position: fixed; inset: 0; z-index: 200;
  background: rgba(0,0,0,0.6); backdrop-filter: blur(4px);
  -webkit-backdrop-filter: blur(4px);
  display: flex; align-items: flex-start; justify-content: center;
  padding-top: 120px;
  opacity: 0; visibility: hidden;
  transition: opacity var(--transition-base), visibility var(--transition-base);
}
.search-overlay.active {
  opacity: 1; visibility: visible;
}
.search-panel {
  background: var(--c-white); border-radius: var(--radius-lg);
  width: 90%; max-width: 640px; max-height: calc(100vh - 200px);
  display: flex; flex-direction: column;
  box-shadow: var(--shadow-xl);
  transform: translateY(-20px) scale(0.97);
  transition: transform var(--transition-base);
  overflow: hidden;
}
.search-overlay.active .search-panel {
  transform: translateY(0) scale(1);
}
.search-input-wrap {
  display: flex; align-items: center; gap: var(--space-sm);
  padding: var(--space-lg); border-bottom: 1px solid var(--c-border);
}
.search-input-wrap svg { color: var(--c-text-muted); flex-shrink: 0; }
.search-input-wrap svg path, .search-input-wrap svg circle, .search-input-wrap svg line { stroke: currentColor; }
.search-input {
  flex: 1; border: none; outline: none; font-size: var(--text-body);
  font-family: var(--font-main); background: transparent;
  color: var(--c-text); padding: 4px 0;
}
.search-input::placeholder { color: var(--c-text-muted); }
.search-results {
  flex: 1; overflow-y: auto; padding: var(--space-md);
}
.search-results-empty {
  text-align: center; padding: var(--space-2xl) var(--space-lg);
  color: var(--c-text-muted); font-size: var(--text-sm);
}
.search-group-title {
  font-size: var(--text-xs); font-weight: 700; color: var(--c-text-muted);
  text-transform: uppercase; letter-spacing: 0.05em;
  padding: var(--space-sm) var(--space-md);
  margin-top: var(--space-sm);
}
.search-result-item {
  display: block; padding: var(--space-md); border-radius: var(--radius-sm);
  text-decoration: none; color: inherit; transition: background var(--transition-fast);
  cursor: pointer;
}
.search-result-item:hover, .search-result-item.focused {
  background: rgba(79,70,229,0.06);
}
.search-result-item .result-title {
  font-size: var(--text-body); font-weight: 600; color: var(--c-text); margin-bottom: 2px;
}
.search-result-item .result-title mark {
  background: rgba(79,70,229,0.15); color: var(--c-primary);
  border-radius: 2px; padding: 0 2px;
}
.search-result-item .result-summary {
  font-size: var(--text-sm); color: var(--c-text-muted);
  display: -webkit-box; -webkit-line-clamp: 1; -webkit-box-orient: vertical; overflow: hidden;
  margin-bottom: 4px;
}
.search-result-item .result-summary mark {
  background: rgba(79,70,229,0.15); color: var(--c-primary);
  border-radius: 2px; padding: 0 2px;
}
.search-result-item .result-domain-tag {
  font-size: var(--text-xs); font-weight: 500; color: var(--c-primary);
  background: rgba(79,70,229,0.08); padding: 2px 8px; border-radius: var(--radius-full);
}
.search-footer {
  padding: var(--space-sm) var(--space-lg); border-top: 1px solid var(--c-border);
  font-size: var(--text-xs); color: var(--c-text-muted); text-align: center;
}
.search-footer kbd {
  padding: 1px 4px; border-radius: 3px;
  background: var(--c-bg-alt); border: 1px solid var(--c-border);
  font-family: var(--font-mono); margin: 0 2px;
}

/* ---------- Bookmark (收藏) Button ---------- */
.bookmark-nav-btn {
  background: none; border: none; cursor: pointer;
  padding: var(--space-xs) var(--space-sm);
  color: var(--c-text); font-size: var(--text-sm);
  transition: color var(--transition-fast), transform var(--transition-fast);
  border-radius: var(--radius-sm);
  display: flex; align-items: center; gap: 4px;
  position: relative;
}
.bookmark-nav-btn:hover {
  color: var(--c-primary);
  background: rgba(79,70,229,0.06);
}
.bookmark-badge {
  position: absolute; top: -2px; right: -2px;
  background: var(--c-danger); color: #fff;
  font-size: 10px; font-weight: 700;
  min-width: 16px; height: 16px;
  border-radius: 8px; display: flex; align-items: center; justify-content: center;
  padding: 0 4px;
}
.bookmark-badge:empty, .bookmark-badge[data-count="0"] { display: none; }

/* Bookmark article button */
.article-bookmark-btn {
  display: inline-flex; align-items: center; gap: 6px;
  padding: 8px 16px; border: 1px solid var(--c-border); border-radius: var(--radius-sm);
  background: var(--c-bg-alt); color: var(--c-text-muted);
  font-size: var(--text-sm); font-weight: 500; cursor: pointer;
  transition: all var(--transition-fast); font-family: var(--font-main);
  margin-top: var(--space-xl);
}
.article-bookmark-btn:hover {
  border-color: var(--c-primary); color: var(--c-primary);
  background: rgba(79,70,229,0.04);
}
.article-bookmark-btn.bookmarked {
  background: rgba(79,70,229,0.1); border-color: var(--c-primary);
  color: var(--c-primary);
}

/* ---------- Bookmark Sidebar Panel ---------- */
.bookmark-panel-overlay {
  position: fixed; inset: 0; z-index: 201;
  background: rgba(0,0,0,0.4);
  opacity: 0; visibility: hidden;
  transition: opacity var(--transition-base), visibility var(--transition-base);
}
.bookmark-panel-overlay.active {
  opacity: 1; visibility: visible;
}
.bookmark-panel {
  position: fixed; top: 0; right: 0; bottom: 0; z-index: 202;
  width: 380px; max-width: 90vw;
  background: var(--c-white);
  box-shadow: -4px 0 20px rgba(0,0,0,0.15);
  display: flex; flex-direction: column;
  transform: translateX(100%);
  transition: transform var(--transition-base);
}
.bookmark-panel-overlay.active + .bookmark-panel,
.bookmark-panel.active {
  transform: translateX(0);
}
.bookmark-panel-header {
  display: flex; align-items: center; justify-content: space-between;
  padding: var(--space-lg); border-bottom: 1px solid var(--c-border);
}
.bookmark-panel-header h3 {
  font-size: var(--text-body); font-weight: 700; color: var(--c-text);
  margin: 0;
}
.bookmark-panel-close {
  background: none; border: none; cursor: pointer;
  color: var(--c-text-muted); padding: 4px; border-radius: var(--radius-sm);
  transition: color var(--transition-fast);
}
.bookmark-panel-close:hover { color: var(--c-text); }
.bookmark-panel-list {
  flex: 1; overflow-y: auto; padding: var(--space-md);
}
.bookmark-panel-empty {
  text-align: center; padding: var(--space-2xl) var(--space-lg);
  color: var(--c-text-muted); font-size: var(--text-sm);
}
.bookmark-panel-item {
  display: flex; align-items: center; gap: var(--space-sm);
  padding: var(--space-md); border-radius: var(--radius-sm);
  border-bottom: 1px solid var(--c-border);
  text-decoration: none; color: inherit; transition: background var(--transition-fast);
}
.bookmark-panel-item:hover { background: rgba(79,70,229,0.04); }
.bookmark-panel-item-info { flex: 1; min-width: 0; }
.bookmark-panel-item-title {
  font-size: var(--text-sm); font-weight: 600; color: var(--c-text);
  white-space: nowrap; overflow: hidden; text-overflow: ellipsis;
}
.bookmark-panel-item-domain {
  font-size: var(--text-xs); color: var(--c-text-muted);
}
.bookmark-panel-remove {
  background: none; border: none; cursor: pointer;
  color: var(--c-text-muted); padding: 4px; border-radius: var(--radius-sm);
  transition: all var(--transition-fast); font-size: 16px; line-height: 1;
  flex-shrink: 0;
}
.bookmark-panel-remove:hover { color: var(--c-danger); }

/* ---------- Scrollbar for search ---------- */
.search-results::-webkit-scrollbar,
.bookmark-panel-list::-webkit-scrollbar {
  width: 6px;
}
.search-results::-webkit-scrollbar-track,
.bookmark-panel-list::-webkit-scrollbar-track {
  background: transparent;
}
.search-results::-webkit-scrollbar-thumb,
.bookmark-panel-list::-webkit-scrollbar-thumb {
  background: var(--c-border); border-radius: 3px;
}

/* ---------- Responsive for search/bookmark panels ---------- */
@media (max-width: 767px) {
  .search-overlay { padding-top: 60px; }
  .search-panel { width: 95%; max-height: calc(100vh - 80px); }
}