/* ========== CSS VARIABLES / DESIGN TOKENS ========== */
:root {
  --font-main: 'Inter', -apple-system, BlinkMacSystemFont, sans-serif;
  --font-mono: 'Fira Code', 'Consolas', monospace;
  --radius-sm: 6px;
  --radius-md: 12px;
  --radius-lg: 20px;
  --transition: 0.3s cubic-bezier(0.4, 0, 0.2, 1);
  --sidebar-width: 280px;
  --sidebar-collapsed-width: 60px;
}

[data-theme="dark"] {
  --bg-primary: #0a0e1a;
  --bg-secondary: #111827;
  --bg-card: rgba(255,255,255,0.05);
  --bg-card-hover: rgba(255,255,255,0.1);
  --bg-surface: rgba(255,255,255,0.03);
  --text-primary: #f0f4f8;
  --text-secondary: #94a3b8;
  --text-muted: #64748b;
  --border-color: rgba(255,255,255,0.08);
  --border-glow: rgba(0,212,255,0.15);
  --accent-1: #00d4ff;
  --accent-2: #7b2ff7;
  --accent-3: #ff2d55;
  --gradient-accent: linear-gradient(135deg, #00d4ff, #7b2ff7);
  --gradient-accent-2: linear-gradient(135deg, #7b2ff7, #ff2d55);
  --shadow-card: 0 4px 24px rgba(0,0,0,0.3);
  --shadow-glow: 0 0 20px rgba(0,212,255,0.1);
  --canvas-bg: #0d1117;
  --code-bg: #1e1e2e;
  --scrollbar-track: #1a1a2e;
  --scrollbar-thumb: #334155;
  --overlay: rgba(0,0,0,0.5);
}

[data-theme="light"] {
  --bg-primary: #f8fafc;
  --bg-secondary: #ffffff;
  --bg-card: rgba(0,0,0,0.03);
  --bg-card-hover: rgba(0,0,0,0.06);
  --bg-surface: rgba(0,0,0,0.02);
  --text-primary: #1e293b;
  --text-secondary: #475569;
  --text-muted: #94a3b8;
  --border-color: rgba(0,0,0,0.1);
  --border-glow: rgba(123,47,247,0.15);
  --accent-1: #0091d4;
  --accent-2: #6d28d9;
  --accent-3: #e11d48;
  --gradient-accent: linear-gradient(135deg, #0091d4, #6d28d9);
  --gradient-accent-2: linear-gradient(135deg, #6d28d9, #e11d48);
  --shadow-card: 0 4px 24px rgba(0,0,0,0.08);
  --shadow-glow: 0 0 20px rgba(123,47,247,0.08);
  --canvas-bg: #ffffff;
  --code-bg: #f5f5f5;
  --scrollbar-track: #e2e8f0;
  --scrollbar-thumb: #94a3b8;
  --overlay: rgba(0,0,0,0.3);
}

/* ========== RESET & BASE ========== */
*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }
html { scroll-behavior: smooth; }
body {
  font-family: var(--font-main);
  background: var(--bg-primary);
  color: var(--text-primary);
  min-height: 100vh;
  overflow-x: hidden;
  transition: background var(--transition), color var(--transition);
}
a { color: inherit; text-decoration: none; }
button { font-family: inherit; cursor: pointer; border: none; background: none; color: inherit; }
input, select { font-family: inherit; }
::-webkit-scrollbar { width: 6px; height: 6px; }
::-webkit-scrollbar-track { background: var(--scrollbar-track); }
::-webkit-scrollbar-thumb { background: var(--scrollbar-thumb); border-radius: 3px; }

/* ========== LAYOUT ========== */
.app-layout {
  display: flex;
  min-height: 100vh;
}

/* Sidebar */
.sidebar {
  width: var(--sidebar-width);
  background: var(--bg-secondary);
  border-right: 1px solid var(--border-color);
  display: flex;
  flex-direction: column;
  position: fixed;
  top: 0; left: 0; bottom: 0;
  z-index: 100;
  transition: width var(--transition), transform var(--transition);
  overflow-y: auto;
  overflow-x: hidden;
}
.sidebar.collapsed {
  width: var(--sidebar-collapsed-width);
}
.sidebar.collapsed ~ .main-content {
  margin-left: var(--sidebar-collapsed-width);
}
/* Collapsed sidebar: hide text, show icons */
.sidebar.collapsed .sidebar-collapse-btn {
  display: none;
}
.sidebar.collapsed .sidebar-search {
  display: none;
}
.sidebar.collapsed .sidebar-footer {
  display: none;
}
.sidebar.collapsed .sidebar-header {
  padding: 12px 0;
  justify-content: center;
}
.sidebar.collapsed .nav-category-title {
  font-size: 0;
  padding: 8px 0 4px;
  text-align: center;
  border-bottom: 1px solid var(--border-color);
  margin: 0 10px;
  line-height: 0;
  min-height: 1px;
}
.sidebar.collapsed .nav-category {
  padding: 0;
}
.sidebar.collapsed .nav-item {
  justify-content: center;
  padding: 10px 0;
  gap: 0;
  position: relative;
  border-radius: 0;
  margin: 2px 8px;
  border-radius: var(--radius-sm);
}
.sidebar.collapsed .nav-item span:not(.nav-icon) {
  display: none;
}
.sidebar.collapsed .nav-item .nav-icon {
  font-size: 1.15rem;
  width: auto;
}
/* Tooltip on hover for collapsed sidebar items */
.sidebar.collapsed .nav-item::after {
  content: attr(data-tooltip);
  position: absolute;
  left: calc(100% + 12px);
  top: 50%;
  transform: translateY(-50%) scale(0.92);
  background: var(--bg-secondary);
  color: var(--text-primary);
  padding: 6px 14px;
  border-radius: var(--radius-sm);
  font-size: 0.78rem;
  font-weight: 600;
  white-space: nowrap;
  opacity: 0;
  pointer-events: none;
  transition: all 0.2s cubic-bezier(0.4, 0, 0.2, 1);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-card);
  z-index: 200;
  letter-spacing: 0;
}
.sidebar.collapsed .nav-item:hover::after {
  opacity: 1;
  transform: translateY(-50%) scale(1);
}
.sidebar-header {
  padding: 14px 20px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: flex-end;
  min-height: 52px;
}
/* Navbar Logo (centered in top bar) */
.navbar-logo {
  font-size: 1.3rem;
  font-weight: 800;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -0.3px;
  position: absolute;
  left: 50%;
  transform: translateX(-50%);
  white-space: nowrap;
  transition: opacity var(--transition);
}
.navbar-logo:hover {
  opacity: 0.8;
}
.sidebar-collapse-btn {
  width: 28px; height: 28px;
  border-radius: 6px;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  font-size: 0.65rem;
  color: var(--text-muted);
  transition: all var(--transition);
  flex-shrink: 0;
}
.sidebar-collapse-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-1);
  color: var(--accent-1);
}
/* Expand button inside collapsed sidebar */
.sidebar-expand-area {
  display: none;
  padding: 8px;
}
.sidebar.collapsed .sidebar-expand-area {
  display: flex;
  justify-content: center;
}
.sidebar-expand-btn {
  width: 36px; height: 36px;
  border-radius: var(--radius-sm);
  display: flex;
  align-items: center; justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  font-size: 0.75rem;
  color: var(--text-muted);
  transition: all var(--transition);
}
.sidebar-expand-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-1);
  color: var(--accent-1);
  box-shadow: var(--shadow-glow);
}
.sidebar-search {
  padding: 12px 20px;
}
.sidebar-search input {
  width: 100%;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 0.85rem;
  outline: none;
  transition: border-color var(--transition), box-shadow var(--transition);
}
.sidebar-search input:focus {
  border-color: var(--accent-1);
  box-shadow: 0 0 0 3px rgba(0,212,255,0.1);
}
.sidebar-nav { flex: 1; padding: 8px 0; overflow-y: auto; }
.nav-category {
  padding: 0 12px;
  margin-bottom: 4px;
}
.nav-category-title {
  font-size: 0.7rem;
  font-weight: 700;
  text-transform: uppercase;
  letter-spacing: 1.5px;
  color: var(--text-muted);
  padding: 12px 8px 6px;
}
.nav-item {
  display: flex;
  align-items: center;
  gap: 10px;
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  font-size: 0.85rem;
  color: var(--text-secondary);
  transition: all var(--transition);
  cursor: pointer;
}
.nav-item:hover {
  background: var(--bg-card-hover);
  color: var(--text-primary);
}
.nav-item.active {
  background: var(--bg-card-hover);
  color: var(--accent-1);
  font-weight: 600;
}
.nav-item .nav-icon { font-size: 1rem; width: 20px; text-align: center; }

.sidebar-footer {
  padding: 16px 20px;
  border-top: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
}

/* Main Content */
.main-content {
  flex: 1;
  margin-left: var(--sidebar-width);
  min-height: 100vh;
  display: flex;
  flex-direction: column;
}

/* Top Bar */
.top-bar {
  display: flex;
  align-items: center;
  justify-content: space-between;
  padding: 16px 32px;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-secondary);
  position: sticky;
  top: 0;
  z-index: 50;
  backdrop-filter: blur(12px);
}
.breadcrumb {
  display: flex;
  align-items: center;
  gap: 8px;
  font-size: 0.9rem;
  color: var(--text-secondary);
}
.breadcrumb .sep { color: var(--text-muted); }
.breadcrumb .current { color: var(--text-primary); font-weight: 600; }
.top-bar-actions { display: flex; align-items: center; gap: 10px; }

/* GitHub Icon + Tooltip */
.github-link-wrapper {
  position: relative;
  display: flex;
  align-items: center;
}
.github-link {
  width: 38px; height: 38px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
  transition: all var(--transition);
}
.github-link:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-1);
  color: var(--accent-1);
  box-shadow: var(--shadow-glow);
  transform: scale(1.05);
}
.github-tooltip {
  position: absolute;
  top: calc(100% + 10px);
  right: 0;
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-sm);
  padding: 8px 14px;
  font-size: 0.78rem;
  color: var(--text-primary);
  white-space: nowrap;
  box-shadow: var(--shadow-card);
  opacity: 0;
  visibility: hidden;
  transform: translateY(-4px);
  transition: all 0.25s ease;
  z-index: 200;
  pointer-events: none;
}
.github-tooltip::before {
  content: '';
  position: absolute;
  top: -5px; right: 14px;
  width: 8px; height: 8px;
  background: var(--bg-secondary);
  border-left: 1px solid var(--border-color);
  border-top: 1px solid var(--border-color);
  transform: rotate(45deg);
}
.github-link-wrapper:hover .github-tooltip {
  opacity: 1;
  visibility: visible;
  transform: translateY(0);
}

.theme-toggle {
  width: 38px; height: 38px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  font-size: 1.05rem;
  transition: all var(--transition);
}
.theme-toggle:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-1);
  box-shadow: var(--shadow-glow);
  transform: scale(1.05);
}
.hamburger {
  display: none;
  width: 38px; height: 38px;
  border-radius: var(--radius-sm);
  align-items: center; justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  font-size: 1.2rem;
}

/* ========== HOME VIEW ========== */
.home-view { padding: 32px; animation: fadeIn 0.4s ease; }
.home-hero {
  text-align: center;
  padding: 56px 24px 48px;
  margin-bottom: 48px;
  position: relative;
  overflow: hidden;
  border-radius: var(--radius-lg);
  background: var(--bg-card);
  border: 1px solid var(--border-color);
}
.home-hero::before {
  content: '';
  position: absolute;
  top: -50%; left: -50%;
  width: 200%; height: 200%;
  background: conic-gradient(from 0deg at 50% 50%, transparent 0deg, var(--accent-1) 60deg, transparent 120deg, var(--accent-2) 180deg, transparent 240deg, var(--accent-3) 300deg, transparent 360deg);
  opacity: 0.04;
  animation: heroRotate 20s linear infinite;
}
@keyframes heroRotate { from { transform: rotate(0deg); } to { transform: rotate(360deg); } }
.home-hero::after {
  content: '';
  position: absolute;
  inset: 1px;
  background: var(--bg-card);
  border-radius: calc(var(--radius-lg) - 1px);
  z-index: 0;
}
.home-hero > * { position: relative; z-index: 1; }
.home-hero h1 {
  font-size: 3rem;
  font-weight: 800;
  margin-bottom: 16px;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
  letter-spacing: -1px;
}
.home-hero p {
  font-size: 1.05rem;
  color: var(--text-secondary);
  max-width: 580px;
  margin: 0 auto;
  line-height: 1.7;
}
.home-stats {
  display: flex;
  justify-content: center;
  gap: 48px;
  margin-top: 36px;
}
.stat-item { text-align: center; }
.stat-value {
  font-size: 2.2rem;
  font-weight: 800;
  background: var(--gradient-accent);
  -webkit-background-clip: text;
  -webkit-text-fill-color: transparent;
  background-clip: text;
}
.stat-label {
  font-size: 0.75rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1.5px;
  margin-top: 6px;
  font-weight: 600;
}

.category-section { margin-bottom: 40px; }
.category-header {
  display: flex;
  align-items: center;
  gap: 10px;
  margin-bottom: 20px;
  padding-bottom: 12px;
  border-bottom: 1px solid var(--border-color);
}
.category-header .cat-icon { font-size: 1.4rem; }
.category-header h2 {
  font-size: 1.3rem;
  font-weight: 700;
}
.category-header .cat-count {
  font-size: 0.75rem;
  background: var(--bg-card);
  padding: 2px 10px;
  border-radius: 99px;
  color: var(--text-muted);
}

.algo-cards-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}
.algo-card {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  border-radius: var(--radius-md);
  padding: 24px;
  cursor: pointer;
  transition: all 0.35s cubic-bezier(0.4, 0, 0.2, 1);
  position: relative;
  overflow: hidden;
}
.algo-card::before {
  content: '';
  position: absolute;
  top: 0; left: 0; right: 0;
  height: 2px;
  background: var(--gradient-accent);
  opacity: 0;
  transition: opacity var(--transition);
}
.algo-card::after {
  content: '';
  position: absolute;
  inset: 0;
  border-radius: var(--radius-md);
  opacity: 0;
  background: radial-gradient(circle at var(--mouse-x, 50%) var(--mouse-y, 50%), rgba(0,212,255,0.08), transparent 60%);
  transition: opacity var(--transition);
  pointer-events: none;
}
.algo-card:hover {
  background: var(--bg-card-hover);
  border-color: var(--border-glow);
  box-shadow: 0 8px 32px rgba(0,0,0,0.2), var(--shadow-glow);
  transform: translateY(-6px);
}
.algo-card:hover::before { opacity: 1; }
.algo-card:hover::after { opacity: 1; }
.algo-card-icon {
  font-size: 1.8rem;
  margin-bottom: 14px;
  display: inline-block;
  transition: transform 0.3s ease;
}
.algo-card:hover .algo-card-icon { transform: scale(1.15) rotate(-3deg); }
.algo-card h3 {
  font-size: 0.95rem;
  font-weight: 700;
  margin-bottom: 8px;
  letter-spacing: -0.2px;
}
.algo-card p {
  font-size: 0.78rem;
  color: var(--text-secondary);
  line-height: 1.55;
  margin-bottom: 14px;
}
.algo-card-tags { display: flex; flex-wrap: wrap; gap: 5px; }
.tag {
  font-size: 0.6rem;
  padding: 3px 8px;
  border-radius: 99px;
  background: rgba(0,212,255,0.08);
  color: var(--accent-1);
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 0.5px;
  border: 1px solid rgba(0,212,255,0.12);
}

/* ========== ALGORITHM VIEW ========== */
.algo-view {
  display: none;
  flex-direction: column;
  flex: 1;
  animation: fadeIn 0.4s ease;
}
.algo-view.active { display: flex; }
.algo-header-bar {
  padding: 20px 32px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  align-items: center;
  justify-content: space-between;
  flex-wrap: wrap;
  gap: 12px;
}
.algo-title-area h2 {
  font-size: 1.4rem;
  font-weight: 700;
  margin-bottom: 4px;
}
.algo-title-area .algo-desc {
  font-size: 0.85rem;
  color: var(--text-secondary);
}
.algo-how-it-works {
  margin-top: 10px;
  font-size: 0.8rem;
  color: var(--text-secondary);
  line-height: 1.6;
}
.algo-how-it-works .how-label {
  font-weight: 700;
  font-size: 0.72rem;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--accent-1);
  margin-bottom: 6px;
  cursor: pointer;
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.algo-how-it-works .how-label:hover { opacity: 0.8; }
.algo-how-it-works .how-steps {
  display: none;
  padding-left: 4px;
}
.algo-how-it-works .how-steps.open {
  display: block;
}
.algo-how-it-works .how-step {
  display: flex;
  gap: 8px;
  margin-bottom: 4px;
  align-items: flex-start;
}
.algo-how-it-works .how-num {
  font-weight: 700;
  color: var(--accent-2);
  min-width: 18px;
  font-size: 0.75rem;
}
.complexity-badges { display: flex; gap: 8px; flex-shrink: 0; }
.badge {
  font-size: 0.7rem;
  padding: 4px 12px;
  border-radius: 99px;
  font-weight: 600;
  border: 1px solid var(--border-color);
  background: var(--bg-card);
}
.badge.time { color: var(--accent-1); }
.badge.space { color: var(--accent-2); }

.algo-body {
  display: flex;
  flex: 1;
  overflow: hidden;
}

/* Input Panel */
.input-panel {
  padding: 16px;
  border-bottom: 1px solid var(--border-color);
  display: flex;
  flex-wrap: wrap;
  gap: 10px;
  align-items: flex-end;
  background: var(--bg-surface);
}
.input-group { display: flex; flex-direction: column; gap: 4px; }
.input-group label {
  font-size: 0.7rem;
  font-weight: 600;
  text-transform: uppercase;
  letter-spacing: 1px;
  color: var(--text-muted);
}
.input-group input, .input-group select {
  padding: 8px 12px;
  border-radius: var(--radius-sm);
  border: 1px solid var(--border-color);
  background: var(--bg-card);
  color: var(--text-primary);
  font-size: 0.85rem;
  outline: none;
  transition: all var(--transition);
}
.input-group input:focus, .input-group select:focus {
  border-color: var(--accent-1);
  box-shadow: 0 0 0 3px rgba(0,212,255,0.1);
}
.btn {
  padding: 8px 16px;
  border-radius: var(--radius-sm);
  font-size: 0.8rem;
  font-weight: 600;
  transition: all var(--transition);
  display: inline-flex;
  align-items: center;
  gap: 6px;
}
.btn-primary {
  background: var(--gradient-accent);
  color: #fff;
}
.btn-primary:hover { opacity: 0.9; transform: translateY(-1px); }
.btn-secondary {
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  color: var(--text-secondary);
}
.btn-secondary:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-1);
  color: var(--text-primary);
}

/* Visualization Area */
.viz-area {
  flex: 1;
  display: flex;
  flex-direction: column;
  min-width: 0;
}
.canvas-container {
  flex: 1;
  position: relative;
  background: var(--canvas-bg);
  overflow: hidden;
  min-height: 350px;
}
.canvas-container canvas {
  width: 100%;
  height: 100%;
  display: block;
}
.step-info {
  padding: 10px 16px;
  font-size: 0.85rem;
  color: var(--text-secondary);
  background: var(--bg-surface);
  border-top: 1px solid var(--border-color);
  min-height: 38px;
  display: flex;
  align-items: center;
  gap: 8px;
}
.step-info .step-desc { flex: 1; }
.step-info .step-counter {
  font-size: 0.75rem;
  color: var(--text-muted);
  font-weight: 600;
  white-space: nowrap;
}

/* Controls Bar */
.controls-bar {
  display: flex;
  align-items: center;
  justify-content: center;
  gap: 8px;
  padding: 12px 16px;
  border-top: 1px solid var(--border-color);
  background: var(--bg-secondary);
}
.ctrl-btn {
  width: 36px; height: 36px;
  border-radius: 50%;
  display: flex; align-items: center; justify-content: center;
  background: var(--bg-card);
  border: 1px solid var(--border-color);
  font-size: 0.9rem;
  transition: all var(--transition);
}
.ctrl-btn:hover {
  background: var(--bg-card-hover);
  border-color: var(--accent-1);
  color: var(--accent-1);
}
.ctrl-btn.play-btn {
  width: 44px; height: 44px;
  background: var(--gradient-accent);
  border: none;
  color: #fff;
  font-size: 1.1rem;
}
.ctrl-btn.play-btn:hover { opacity: 0.9; transform: scale(1.05); }
.speed-control {
  display: flex;
  align-items: center;
  gap: 8px;
  margin-left: 16px;
  padding-left: 16px;
  border-left: 1px solid var(--border-color);
}
.speed-control label {
  font-size: 0.7rem;
  color: var(--text-muted);
  text-transform: uppercase;
  letter-spacing: 1px;
  font-weight: 600;
}
.speed-control input[type="range"] {
  width: 80px;
  accent-color: var(--accent-1);
}
.speed-value {
  font-size: 0.75rem;
  color: var(--accent-1);
  font-weight: 700;
  min-width: 30px;
}

/* Panel Resizer Handle */
.panel-resizer {
  width: 6px;
  cursor: col-resize;
  background: var(--border-color);
  position: relative;
  flex-shrink: 0;
  transition: background 0.2s ease;
  z-index: 10;
}
.panel-resizer::after {
  content: '⋮';
  position: absolute;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  font-size: 14px;
  color: var(--text-muted);
  letter-spacing: -2px;
  pointer-events: none;
}
.panel-resizer:hover, .panel-resizer.active {
  background: var(--accent-1);
}
.panel-resizer:hover::after, .panel-resizer.active::after {
  color: #fff;
}

/* Code Panel */
.code-panel {
  width: 420px;
  min-width: 200px;
  max-width: 60%;
  border-left: none;
  display: flex;
  flex-direction: column;
  background: var(--bg-secondary);
  overflow: hidden;
}
.code-tabs {
  display: flex;
  border-bottom: 1px solid var(--border-color);
  background: var(--bg-surface);
}
.code-tab {
  padding: 10px 16px;
  font-size: 0.8rem;
  font-weight: 600;
  color: var(--text-muted);
  border-bottom: 2px solid transparent;
  transition: all var(--transition);
}
.code-tab:hover { color: var(--text-secondary); }
.code-tab.active {
  color: var(--accent-1);
  border-bottom-color: var(--accent-1);
}
.code-copy-btn {
  margin-left: auto;
  padding: 8px 12px;
  font-size: 0.75rem;
  color: var(--text-muted);
  transition: color var(--transition);
}
.code-copy-btn:hover { color: var(--accent-1); }
.code-content {
  flex: 1;
  overflow-y: auto;
  overflow-x: hidden;
  padding: 16px 0;
  background: var(--code-bg);
  font-family: var(--font-mono);
  font-size: 0.78rem;
  line-height: 1.75;
}
.code-content::-webkit-scrollbar { width: 6px; }
.code-content::-webkit-scrollbar-track { background: transparent; }
.code-content::-webkit-scrollbar-thumb { background: var(--text-muted); border-radius: 3px; }
.code-line {
  display: flex;
  padding: 1px 16px;
  transition: background var(--transition);
}
.code-line.active {
  background: rgba(0,212,255,0.1);
  border-left: 3px solid var(--accent-1);
  padding-left: 13px;
}
.code-line-num {
  width: 32px;
  text-align: right;
  padding-right: 12px;
  color: var(--text-muted);
  user-select: none;
  flex-shrink: 0;
}
.code-line-text {
  flex: 1;
  white-space: pre-wrap;
  word-break: break-word;
  overflow-wrap: break-word;
}
/* Syntax colors */
.syn-kw { color: #c678dd; }
.syn-fn { color: #61afef; }
.syn-str { color: #98c379; }
.syn-num { color: #d19a66; }
.syn-cmt { color: #5c6370; font-style: italic; }
.syn-type { color: #e5c07b; }
.syn-op { color: #56b6c2; }

/* ========== TOAST ========== */
.toast-container {
  position: fixed;
  bottom: 24px; right: 24px;
  z-index: 1000;
  display: flex;
  flex-direction: column;
  gap: 8px;
}
.toast {
  padding: 12px 20px;
  border-radius: var(--radius-sm);
  background: var(--bg-secondary);
  border: 1px solid var(--border-color);
  box-shadow: var(--shadow-card);
  font-size: 0.85rem;
  animation: slideUp 0.3s ease;
  display: flex;
  align-items: center;
  gap: 8px;
}
.toast.success { border-left: 3px solid #10b981; }
.toast.error { border-left: 3px solid var(--accent-3); }

/* ========== ANIMATIONS ========== */
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: translateY(0); } }
@keyframes slideUp { from { opacity: 0; transform: translateY(20px); } to { opacity: 1; transform: translateY(0); } }
@keyframes pulse { 0%, 100% { opacity: 1; } 50% { opacity: 0.5; } }
@keyframes shimmer {
  0% { background-position: -200% 0; }
  100% { background-position: 200% 0; }
}

/* ========== RESPONSIVE ========== */
@media (max-width: 1024px) {
  .code-panel { width: 320px; min-width: 260px; }
}
@media (max-width: 768px) {
  .sidebar { transform: translateX(-100%); width: var(--sidebar-width); }
  .sidebar.open { transform: translateX(0); }
  .sidebar.collapsed { transform: translateX(-100%); width: var(--sidebar-width); }
  .main-content { margin-left: 0 !important; }
  .hamburger { display: flex; }
  .sidebar-collapse-btn { display: none; }
  .sidebar-expand-area { display: none !important; }
  .algo-body { flex-direction: column; }
  .code-panel { width: 100%; min-width: auto; border-left: none; border-top: 1px solid var(--border-color); max-height: 300px; }
  .home-hero h1 { font-size: 2rem; }
  .algo-cards-grid { grid-template-columns: 1fr; }
  .home-stats { gap: 24px; }
}
.sidebar-overlay {
  display: none;
  position: fixed;
  inset: 0;
  background: var(--overlay);
  z-index: 99;
}
.sidebar-overlay.active { display: block; }

/* ========== SELECTION ========== */
::selection {
  background: rgba(0,212,255,0.2);
  color: var(--text-primary);
}