/* ============================================================
   LeetCode Hot 100 图解 — 公共样式
   浅色渐变卡片风格 + 深色主题兼容
   ============================================================ */

/* ---------- CSS Variables (Light Theme — Default) ---------- */
:root {
  /* Light theme vars (used by Style A pages) */
  --blue: #3b82f6; --blue-light: #dbeafe; --blue-dark: #1e40af;
  --green: #16a34a; --green-light: #dcfce7; --green-dark: #166534;
  --purple: #8b5cf6; --purple-light: #ede9fe; --purple-dark: #5b21b6;
  --red: #ef4444; --red-light: #fee2e2; --red-dark: #991b1b;
  --orange: #f59e0b; --orange-light: #fff7ed; --orange-dark: #9a3412;
  --cyan: #06b6d4; --cyan-light: #cffafe;
  --bg: #f1f5f9; --card: #ffffff; --border: #e2e8f0;
  --text: #0f172a; --text-secondary: #475569; --text-muted: #94a3b8;
  --surface: #ffffff; --surface2: #f1f5f9;
  --accent: #3b82f6; --accent2: #2563eb;
  --radius: 12px; --radius-lg: 16px;
  --shadow: 0 1px 3px rgba(0,0,0,0.06);
  --shadow-md: 0 4px 12px rgba(0,0,0,0.08);
  --transition: 0.25s ease;
  --mono: 'Menlo','Consolas','JetBrains Mono','Fira Code',monospace;
  --font: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "PingFang SC", "Microsoft YaHei", sans-serif;

  /* Dark theme compatible vars (used by Style B pages) */
  --green-dim: rgba(22,163,74,.15);
  --red-dim: rgba(239,68,68,.15);
  --orange-dim: rgba(245,158,11,.15);
  --blue-dim: rgba(59,130,246,.15);
  --purple-dim: rgba(139,92,246,.15);
}

*, *::before, *::after { box-sizing: border-box; margin: 0; padding: 0; }

body {
  font-family: var(--font);
  background: linear-gradient(135deg, #f5f7fa 0%, #e4e9f2 50%, #dfe6ed 100%);
  min-height: 100vh;
  color: var(--text);
  line-height: 1.6;
}

/* ---------- Layout ---------- */
.container { max-width: 1440px; margin: 0 auto; padding: 20px; }

/* ---------- Typography ---------- */
h1 { font-size: 25px; margin: 0 0 8px; }
h2 { font-size: 20px; margin: 0 0 12px; color: #1e293b; }
h3 { margin: 0 0 10px; font-size: 16px; }
.subtitle { color: var(--text-secondary); margin-bottom: 16px; font-size: 1.1rem; }

/* ---------- Badge ---------- */
.badge {
  display: inline-block; padding: 2px 10px; border-radius: 999px;
  font-size: 12px; font-weight: 600; margin-left: 8px; vertical-align: middle;
}
.badge.easy   { background: #dcfce7; color: #166534; }
.badge.medium { background: #fef3c7; color: #92400e; }
.badge.hard   { background: #fee2e2; color: #991b1b; }

/* ---------- Controls ---------- */
.controls {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius);
  padding: 12px 16px; display: flex; flex-wrap: wrap; gap: 8px; align-items: center;
  margin-bottom: 12px;
}
.controls label { font-size: .82rem; color: var(--text-secondary); }
.controls input, .controls select {
  padding: 8px 10px; border: 1px solid #cbd5e1; border-radius: 8px;
  font-family: var(--mono); font-size: 14px; background: #f8fafc; color: var(--text);
}
.controls input:focus, .controls select:focus { outline: 2px solid var(--blue); outline-offset: -1px; }
.controls input[type="text"] { width: 260px; }
.controls button {
  padding: 8px 12px; border: 1px solid #cbd5e1; border-radius: 8px;
  background: #f8fafc; font-size: 14px; cursor: pointer; color: var(--text);
  transition: background var(--transition), transform 0.1s;
}
.controls button:hover { background: #e2e8f0; }
.controls button:active { transform: scale(0.97); }
.controls button:disabled { opacity: 0.45; cursor: not-allowed; }
.controls button.primary {
  background: var(--blue); color: white; border-color: var(--blue);
}
.controls button.primary:hover { background: #2563eb; }

/* ---------- Pipeline / Step Indicator ---------- */
.pipeline {
  display: flex; flex-wrap: wrap; align-items: center; gap: 6px;
  background: #eef2ff; border-radius: var(--radius); padding: 10px 16px; margin-bottom: 12px;
  font-size: 14px;
}
.pipe-step {
  background: white; border: 1px solid #c7d2fe; border-radius: 999px;
  padding: 4px 10px; color: #3730a3; transition: all var(--transition);
}
.pipe-step.active {
  background: #4f46e5; color: white; border-color: #4f46e5; font-weight: 600;
  box-shadow: 0 0 0 3px rgba(79,70,229,0.2);
}
.pipeline i { color: var(--text-muted); font-style: normal; }

/* Step dots (Style B) */
.step-dot {
  width: 28px; height: 6px; border-radius: 3px; background: #cbd5e1;
  display: inline-block; transition: background .2s; cursor: pointer;
}
.step-dot.done { background: var(--blue); }
.step-dot.active { background: var(--orange); }

/* ---------- Hint Box ---------- */
.hint {
  background: var(--orange-light); border-left: 4px solid var(--orange); border-radius: 8px;
  padding: 10px 16px; margin-bottom: 12px; line-height: 1.7; font-size: 14px;
}
.hint.info { background: #eff6ff; border-left-color: var(--blue); }
.hint.success { background: #f0fdf4; border-left-color: var(--green); }
.hint #stepInfo { font-weight: 700; }

/* ---------- Cards & Panels ---------- */
.card, .panel {
  background: var(--card); border: 1px solid var(--border); border-radius: var(--radius-lg);
  padding: 20px; margin-bottom: 12px; box-shadow: var(--shadow);
}
.panel-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 16px; }
@media (max-width: 900px) { .panel-grid { grid-template-columns: 1fr; } }
.panels { display: flex; flex-direction: column; gap: 16px; }

/* ---------- Formula / Code Box ---------- */
.formula-box {
  background: #f0f9ff; border-radius: var(--radius); padding: 12px 16px;
  font-size: 15px; line-height: 1.8; margin-bottom: 12px; color: #0c4a6e;
}
.calc-block {
  background: #f8fafc; border-radius: var(--radius); padding: 12px 16px;
  font-size: 15px; line-height: 1.9; margin-bottom: 10px; border: 1px solid var(--border);
}
code {
  background: #f1f5f9; padding: 0.15em 0.4em; border-radius: 4px;
  font-size: 0.9em; color: #7c3aed; font-family: var(--mono);
}
pre {
  background: #f8fafc; border: 1px solid var(--border); border-radius: 8px;
  padding: 1rem; overflow-x: auto; margin: 0.75rem 0;
}
pre code { background: none; padding: 0; color: var(--text); }

/* Code block with highlight */
.code-block {
  margin: 12px 0; border-radius: var(--radius); overflow: hidden;
  border: 1px solid var(--border);
}
.code-block .lang-label {
  background: #e2e8f0; padding: 4px 12px; font-size: 12px; color: var(--text-secondary);
  font-weight: 600;
}
.code-block pre { margin: 0; border: none; border-radius: 0; }
.code-block .hl { background: #fef3c7; display: inline; }
.code-line { display: block; padding: 0 1rem; transition: background 0.2s; }
.code-line.highlight { background: #fef3c7; border-left: 3px solid var(--orange); }

/* ---------- Tables ---------- */
.table-wrap { overflow-x: auto; margin-top: 8px; }
table { border-collapse: collapse; width: 100%; font-size: 13px; }
th, td { border: 1px solid var(--border); padding: 5px 8px; text-align: center; }
th { background: #f8fafc; color: var(--text-secondary); font-weight: 600; }

/* ---------- Chips / Array Cells (Style A) ---------- */
.nums-line { display: flex; flex-wrap: wrap; align-items: center; gap: 6px; margin: 8px 0; }
.chip {
  display: inline-flex; align-items: center; justify-content: center;
  min-width: 40px; height: 36px; padding: 4px 10px;
  border-radius: 10px; font-family: var(--mono); font-weight: 600; font-size: 14px;
  transition: all var(--transition);
}
.chip.default  { background: #e2e8f0; color: var(--text); }
.chip.blue     { background: var(--blue-light); color: var(--blue-dark); }
.chip.green    { background: var(--green-light); color: var(--green-dark); }
.chip.red      { background: var(--red-light); color: var(--red-dark); }
.chip.orange   { background: var(--orange-light); color: var(--orange-dark); }
.chip.purple   { background: var(--purple-light); color: var(--purple-dark); }
.chip.cyan     { background: var(--cyan-light); color: #155e75; }
.chip.active   { box-shadow: 0 0 0 3px rgba(59,130,246,0.3); transform: scale(1.08); }
.chip.selected { background: #bbf7d0; color: var(--green-dark); box-shadow: 0 0 0 2px var(--green); }
.chip.swapped  { background: #fef3c7; color: #92400e; }
.chip.pointer  { border-bottom: 3px solid var(--blue); }
.chip.sorted   { border-bottom: 3px solid var(--green); }
.chip-group { display: inline-flex; flex-direction: column; align-items: center; gap: 2px; }
.chip-index { font-size: 11px; color: var(--text-muted); }

/* ---------- Array Rendering (Style B) ---------- */
.arr-row { display: flex; align-items: flex-end; gap: 4px; justify-content: center; margin: 8px 0; }
.arr-cell { display: flex; flex-direction: column; align-items: center; min-width: 36px; }
.arr-val { font-family: var(--mono); font-size: .82rem; padding: 3px 0; color: var(--text); }
.arr-bar {
  width: 30px; border-radius: 4px 4px 0 0; background: var(--blue); transition: all .25s;
}
.arr-idx { font-family: var(--mono); font-size: .68rem; color: var(--text-secondary); margin-top: 2px; }
.arr-bar.min-price { background: var(--green); box-shadow: 0 0 8px var(--green); }
.arr-bar.current { background: var(--orange); box-shadow: 0 0 8px var(--orange); }
.arr-bar.checking { background: var(--purple); box-shadow: 0 0 6px var(--purple); }
.arr-bar.covered { background: var(--blue); opacity: .7; }
.arr-bar.best { background: var(--green); box-shadow: 0 0 8px var(--green); }
.arr-cell .tag { font-size: .6rem; font-weight: 700; margin-top: 1px; }
.tag-green { color: var(--green); }
.tag-orange { color: var(--orange); }
.tag-blue { color: var(--blue); }

/* ---------- Arrows / Pointers ---------- */
.pointer-arrow {
  display: inline-flex; flex-direction: column; align-items: center;
  font-size: 11px; color: var(--blue); font-weight: 700;
}
.pointer-arrow::before { content: '▼'; font-size: 10px; }
.pointer-arrow.green { color: var(--green); }
.split { font-size: 22px; font-weight: 800; margin: 0 8px; color: var(--text-muted); }

/* ---------- Result / Answer Box ---------- */
.current-answer {
  margin-top: 12px; padding: 10px 16px; background: #ecfdf5; border-radius: 10px;
  font-size: 16px;
}
.final-answer {
  margin-top: 16px; padding: 16px 20px; background: #ecfdf5;
  border: 2px solid #86efac; border-radius: var(--radius); line-height: 1.9;
}
.final-answer b { color: var(--green); }

/* ---------- Complexity Box ---------- */
.complexity {
  margin-top: 10px; font-size: 13px; color: var(--text-secondary);
  padding: 8px 12px; background: #f1f5f9; border-radius: 8px;
}

/* ---------- Tree / Node Visualization ---------- */
.tree-container {
  display: flex; justify-content: center; padding: 20px 0; overflow-x: auto;
}
.tree-node {
  display: inline-flex; flex-direction: column; align-items: center;
  position: relative;
}
.tree-node .node-circle {
  width: 40px; height: 40px; border-radius: 50%; display: flex;
  align-items: center; justify-content: center; font-weight: 700;
  font-size: 14px; background: var(--blue-light); color: var(--blue-dark);
  border: 2px solid var(--blue); transition: all var(--transition);
}
.tree-node .node-circle.active {
  background: #4f46e5; color: white; box-shadow: 0 0 0 4px rgba(79,70,229,0.25);
}
.tree-node .node-circle.visited {
  background: var(--green-light); border-color: var(--green); color: var(--green-dark);
}
.tree-node .node-circle.current {
  background: #fef3c7; border-color: var(--orange); color: var(--orange-dark);
  box-shadow: 0 0 0 4px rgba(245,158,11,0.25);
}

/* ---------- Linked List Visualization ---------- */
.linked-list {
  display: flex; flex-wrap: wrap; align-items: center; gap: 4px; padding: 16px 0;
}
.ll-node {
  display: inline-flex; align-items: center; gap: 0;
  border: 2px solid var(--blue); border-radius: 8px; overflow: hidden;
  transition: all var(--transition);
}
.ll-node .val {
  min-width: 48px; height: 40px; display: flex; align-items: center; justify-content: center;
  font-weight: 700; font-size: 14px; padding: 0 12px; background: var(--blue-light); color: var(--blue-dark);
}
.ll-node .arrow {
  width: 28px; height: 40px; display: flex; align-items: center; justify-content: center;
  background: #f1f5f9; border-left: 1px solid var(--border); font-size: 16px; color: var(--text-muted);
}
.ll-node.active { border-color: var(--green); box-shadow: 0 0 0 3px rgba(22,163,74,0.2); }
.ll-node.active .val { background: var(--green-light); color: var(--green-dark); }
.ll-node.current { border-color: var(--orange); box-shadow: 0 0 0 3px rgba(245,158,11,0.2); }
.ll-node.current .val { background: #fef3c7; color: var(--orange-dark); }
.ll-node.null-node { border-style: dashed; border-color: var(--text-muted); }
.ll-node.null-node .val { background: #f1f5f9; color: var(--text-muted); font-style: italic; font-weight: 400; }
.ll-arrow { font-size: 18px; color: var(--text-muted); margin: 0 2px; }

/* ---------- Grid/Matrix Visualization ---------- */
.grid-viz, .grid-vis {
  display: inline-grid; gap: 2px; padding: 8px 0;
}
.grid-cell {
  width: 40px; height: 40px; display: flex; align-items: center; justify-content: center;
  border: 1px solid var(--border); border-radius: 6px; font-size: 14px;
  font-weight: 600; transition: all var(--transition); background: white;
}
.grid-cell.island { background: var(--blue-light); color: var(--blue-dark); }
.grid-cell.water { background: #e0f2fe; color: #0369a1; }
.grid-cell.visited { background: var(--green-light); border-color: var(--green); }
.grid-cell.current { background: #fef3c7; border-color: var(--orange); box-shadow: 0 0 0 2px rgba(245,158,11,0.3); }
.grid-cell.rotten { background: var(--orange-light); border-color: var(--orange); color: var(--orange-dark); }
.grid-cell.fresh { background: #dcfce7; border-color: var(--green); }
.grid-cell.empty { background: #f1f5f9; color: var(--text-muted); }
.grid-cell.wall { background: #1e293b; color: white; }
.grid-cell.path { background: #dbeafe; border-color: var(--blue); }
/* Style B grid classes */
.grid-cell.highlight { background: var(--blue); color: #fff; border-color: var(--blue); }
.grid-cell.computing { background: var(--orange-light); border-color: var(--orange); }
.grid-cell.origin { background: var(--purple-light); border-color: var(--purple); }

/* String rendering (Style B) */
.str-row { display: flex; gap: 2px; justify-content: center; margin: 8px 0; flex-wrap: wrap; }

/* ---------- Stack / Queue Visualization ---------- */
.stack-container, .queue-container {
  display: flex; flex-direction: column; align-items: center; gap: 2px; min-height: 200px;
  padding: 8px; background: #f8fafc; border: 2px dashed var(--border); border-radius: var(--radius);
}
.stack-item, .queue-item {
  min-width: 80px; padding: 8px 16px; text-align: center; font-weight: 600;
  border-radius: 8px; font-size: 14px; transition: all var(--transition);
  background: var(--blue-light); color: var(--blue-dark); border: 1px solid var(--blue);
}
.stack-item.top, .queue-item.front {
  background: #4f46e5; color: white; border-color: #4f46e5;
}
.stack-item.popped {
  background: var(--red-light); color: var(--red-dark); border-color: var(--red);
  opacity: 0.5;
}

/* ---------- Step Controls ---------- */
.step-controls {
  display: flex; gap: 8px; align-items: center; justify-content: center;
  margin: 16px 0; flex-wrap: wrap;
}
.step-controls button {
  padding: 10px 16px; border: 1px solid #cbd5e1; border-radius: 8px;
  background: #f8fafc; font-size: 14px; cursor: pointer;
  transition: all var(--transition);
}
.step-controls button:hover { background: #e2e8f0; }
.step-controls button:disabled { opacity: .45; cursor: not-allowed; }
.step-controls button.primary { background: var(--blue); color: white; border-color: var(--blue); }
.step-controls button.primary:hover { background: #2563eb; }
.step-counter {
  font-size: 14px; color: var(--text-secondary); min-width: 100px; text-align: center;
}

/* ---------- Vis Area ---------- */
.vis-area { min-height: 120px; padding: 16px 0; position: relative; }
.vis-area svg { display: block; margin: 0 auto; max-width: 100%; }

/* ---------- Animation Helpers ---------- */
@keyframes fadeIn { from { opacity: 0; transform: translateY(8px); } to { opacity: 1; transform: none; } }
@keyframes pulse { 0%,100% { transform: scale(1); } 50% { transform: scale(1.05); } }
@keyframes slideIn { from { opacity: 0; transform: translateX(-12px); } to { opacity: 1; transform: none; } }
.animate-fade { animation: fadeIn 0.3s ease; }
.animate-pulse { animation: pulse 1s infinite; }
.animate-slide { animation: slideIn 0.3s ease; }

/* ---------- Footer ---------- */
footer {
  margin-top: 3rem; text-align: center; color: var(--text-muted);
  font-size: 0.85rem; padding: 16px 0;
}

/* ---------- Responsive ---------- */
@media (max-width: 768px) {
  .container { padding: 12px; }
  h1 { font-size: 20px; }
  .controls { padding: 8px 10px; }
  .controls input[type="text"] { width: 100%; }
  .panel { padding: 12px; }
  .chip { min-width: 32px; height: 30px; font-size: 12px; padding: 2px 6px; }
  .grid-cell { width: 32px; height: 32px; font-size: 12px; }
}

/* ---------- Print ---------- */
@media print {
  body { background: white; }
  .controls, .step-controls { display: none; }
  .card, .panel { box-shadow: none; border: 1px solid #ccc; }
}

/* ---------- Nav page styles ---------- */
.hero { text-align: center; padding: 3rem 1rem; }
.hero h1 { font-size: 2.5rem; margin-bottom: .5rem; justify-content: center; }
.hero p { color: var(--text-secondary); font-size: 1.1rem; }
.stats { display: flex; gap: 1rem; justify-content: center; margin-top: 1.5rem; flex-wrap: wrap; }
.stat-card { background: white; border: 1px solid var(--border); border-radius: 12px; padding: 1rem 1.5rem; text-align: center; box-shadow: var(--shadow); min-width: 100px; }
.stat-card .num { font-size: 2rem; font-weight: 800; }
.stat-card .label { font-size: .85rem; color: var(--text-secondary); }
.category { margin-bottom: 2rem; }
.category h2 { font-size: 1.3rem; margin-bottom: .75rem; padding-bottom: .5rem; border-bottom: 2px solid var(--border); }
.grid { display: grid; grid-template-columns: repeat(auto-fill,minmax(240px,1fr)); gap: 10px; }
.card-link { display: block; background: white; border: 1px solid var(--border); border-radius: 10px; padding: 12px 16px; text-decoration: none; color: var(--text); transition: all .2s; box-shadow: 0 1px 2px rgba(0,0,0,.04); }
.card-link:hover { transform: translateY(-2px); box-shadow: var(--shadow-md); border-color: var(--blue); }
.card-link .id { font-size: .8rem; color: var(--text-muted); }
.card-link .title { font-weight: 600; font-size: .95rem; margin-top: 2px; }

/* ---------- Misc Helpers ---------- */
.processed { opacity: .85; }
.dim { opacity: .3; }
.best-diff { font-weight: 800; color: var(--green); }
.nearest-val { color: var(--green); font-weight: 700; }
.sign-plus { color: var(--green); font-weight: 800; }
.sign-minus { color: var(--red); font-weight: 800; }