/* DSA 視覺化教室 */
:root {
  --bg: #0e1320;
  --panel: #151c2e;
  --panel2: #1a2338;
  --border: #26314d;
  --text: #e7ecf7;
  --muted: #8d97b0;
  --accent: #5b8cff;
  --green: #37c98e;
  --red: #ff6b7a;
  --amber: #ffb454;
  --purple: #b18cff;
  --cyan: #4fd1e0;
  --mono: 'SFMono-Regular', 'JetBrains Mono', Consolas, 'Liberation Mono', Menlo, monospace;
}

* { box-sizing: border-box; }

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

button, select, a { touch-action: manipulation; -webkit-tap-highlight-color: transparent; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Noto Sans TC', 'PingFang TC', 'Microsoft JhengHei', sans-serif;
  line-height: 1.6;
}

a { color: var(--accent); text-decoration: none; }
a:hover { text-decoration: underline; }

.topbar {
  position: sticky;
  top: 0;
  z-index: 10;
  display: flex;
  align-items: center;
  gap: 12px;
  padding: 12px 22px;
  background: rgba(14, 19, 32, 0.92);
  backdrop-filter: blur(6px);
  border-bottom: 1px solid var(--border);
}

.topbar .logo {
  font-size: 17px;
  font-weight: 700;
  color: var(--text);
}
.topbar .logo:hover { text-decoration: none; }
.topbar .logo .accent { color: var(--accent); }
.topbar .crumb { color: var(--muted); font-size: 14px; }

.container { max-width: 1240px; margin: 0 auto; padding: 24px 22px 80px; }

/* ---------- 首頁 ---------- */
.hero { margin: 18px 0 30px; }
.hero h1 { font-size: 30px; margin: 0 0 8px; }
.hero p { color: var(--muted); margin: 0; max-width: 720px; }

.cat-grid {
  display: grid;
  grid-template-columns: repeat(auto-fill, minmax(260px, 1fr));
  gap: 16px;
}

.cat-card {
  display: block;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 14px;
  padding: 18px;
  color: var(--text);
  transition: transform 0.12s ease, border-color 0.12s ease;
}
.cat-card:hover { transform: translateY(-2px); border-color: var(--accent); text-decoration: none; }
.cat-card .icon { font-size: 26px; }
.cat-card h3 { margin: 8px 0 2px; font-size: 17px; }
.cat-card .en { color: var(--accent); font-size: 12px; letter-spacing: 0.4px; }
.cat-card p { color: var(--muted); font-size: 13px; margin: 8px 0 10px; min-height: 40px; }
.cat-card .count { color: var(--muted); font-size: 12px; border-top: 1px solid var(--border); padding-top: 8px; }

/* ---------- 分類頁 ---------- */
.page-head { margin: 8px 0 22px; }
.page-head h1 { font-size: 26px; margin: 0 0 6px; }
.page-head p { color: var(--muted); margin: 0; }
.back-link { font-size: 13px; color: var(--muted); display: inline-block; margin-bottom: 10px; }

.algo-list { display: grid; grid-template-columns: repeat(auto-fill, minmax(320px, 1fr)); gap: 14px; }
.algo-card {
  display: block;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  padding: 16px;
  color: var(--text);
  transition: border-color 0.12s ease;
}
.algo-card:hover { border-color: var(--accent); text-decoration: none; }
.algo-card h3 { margin: 0 0 4px; font-size: 16px; }
.algo-card .en { color: var(--accent); font-size: 12px; }
.algo-card p { color: var(--muted); font-size: 13px; margin: 8px 0 0; }
.chips { display: flex; flex-wrap: wrap; gap: 6px; margin-top: 10px; }
.chip {
  font-size: 12px;
  font-family: var(--mono);
  background: var(--panel2);
  border: 1px solid var(--border);
  color: var(--cyan);
  padding: 1px 8px;
  border-radius: 999px;
}

/* ---------- 演算法頁 ---------- */
.algo-head h1 { font-size: 24px; margin: 0 0 4px; }
.algo-head .en { color: var(--accent); font-size: 13px; }
.algo-head .summary { color: var(--muted); margin: 8px 0 0; max-width: 860px; }

details.teach {
  margin: 18px 0;
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}
details.teach summary {
  cursor: pointer;
  padding: 12px 18px;
  font-weight: 600;
  user-select: none;
  list-style: none;
}
details.teach summary::before { content: '▸ '; color: var(--accent); }
details.teach[open] summary::before { content: '▾ '; }
.teach-body { padding: 0 20px 16px; max-width: 900px; }
.teach-body h4 { margin: 16px 0 6px; color: var(--cyan); font-size: 14px; }
.teach-body p, .teach-body li { color: #c6cede; font-size: 14px; }
.teach-body ul, .teach-body ol { margin: 6px 0; padding-left: 22px; }
.teach-body code {
  font-family: var(--mono);
  font-size: 12.5px;
  background: var(--panel2);
  border: 1px solid var(--border);
  padding: 0 5px;
  border-radius: 5px;
  color: var(--amber);
}

.workspace {
  display: grid;
  grid-template-columns: minmax(0, 7fr) minmax(0, 5fr);
  gap: 16px;
  align-items: start;
}
/* minmax(0, 1fr)：避免 SVG / 程式碼的固有寬度把欄位撐超出螢幕 */
@media (max-width: 980px) { .workspace { grid-template-columns: minmax(0, 1fr); } }

.pane {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 12px;
  overflow: hidden;
}
.pane-head {
  display: flex;
  align-items: center;
  justify-content: space-between;
  gap: 10px;
  padding: 10px 14px;
  border-bottom: 1px solid var(--border);
  font-size: 13px;
  color: var(--muted);
}

.viz-canvas { padding: 12px 10px 4px; min-height: 200px; }
.viz-block + .viz-block { margin-top: 4px; }
.viz-title { font-size: 12px; color: var(--muted); padding: 2px 14px; }
.viz-svg { width: 100%; height: auto; display: block; }

.note {
  min-height: 44px;
  margin: 6px 14px;
  padding: 9px 13px;
  background: var(--panel2);
  border: 1px solid var(--border);
  border-radius: 9px;
  font-size: 13.5px;
  color: #d7deec;
}

.controls {
  display: flex;
  align-items: center;
  flex-wrap: wrap;
  gap: 8px;
  padding: 10px 14px 14px;
}
.controls button {
  background: var(--panel2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 7px 12px;
  font-size: 14px;
  cursor: pointer;
  transition: border-color 0.1s ease;
}
.controls button:hover:not(:disabled) { border-color: var(--accent); }
.controls button:disabled { opacity: 0.4; cursor: default; }
.controls button.play-btn {
  background: var(--accent);
  border-color: var(--accent);
  color: #fff;
  min-width: 74px;
  font-weight: 600;
}
.controls select {
  background: var(--panel2);
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 8px;
  padding: 6px 8px;
  font-size: 13px;
}
.controls .step-info { font-family: var(--mono); font-size: 12.5px; color: var(--muted); margin-left: auto; }

.seek-row { display: flex; align-items: center; gap: 10px; padding: 0 14px 4px; }
.seek-row input[type='range'] { flex: 1; accent-color: var(--accent); }

/* 程式碼面板 */
.lang-tabs { display: flex; gap: 6px; }
.lang-tabs button {
  background: transparent;
  color: var(--muted);
  border: 1px solid transparent;
  border-radius: 7px;
  padding: 4px 12px;
  font-size: 13px;
  cursor: pointer;
}
.lang-tabs button.active {
  background: var(--panel2);
  color: var(--text);
  border-color: var(--border);
}

.code-scroll { overflow-x: auto; max-height: 480px; overflow-y: auto; }
.code {
  margin: 0;
  padding: 10px 0;
  font-family: var(--mono);
  font-size: 13px;
  line-height: 1.65;
  min-width: max-content;
}
.code .cl { display: flex; padding: 0 14px 0 0; white-space: pre; }
.code .cl.hl { background: rgba(91, 140, 255, 0.16); box-shadow: inset 3px 0 0 var(--accent); }
.code .ln {
  width: 44px;
  flex: none;
  text-align: right;
  padding-right: 14px;
  color: #55617e;
  user-select: none;
}
.tok-k { color: #c792ea; }
.tok-n { color: #f78c6c; }
.tok-s { color: #c3e88d; }
.tok-c { color: #5f6c8c; font-style: italic; }

/* 變數表 */
.vars-table { width: 100%; border-collapse: collapse; font-family: var(--mono); font-size: 12.5px; }
.vars-table th, .vars-table td {
  text-align: left;
  padding: 5px 14px;
  border-bottom: 1px solid var(--border);
}
.vars-table th { color: var(--muted); font-weight: 500; background: var(--panel2); }
.vars-table td.k { color: var(--cyan); width: 130px; }
.vars-table td.v { color: #e5ebf8; word-break: break-all; }
.vars-table tr.changed td.v { color: var(--amber); font-weight: 600; }
.vars-table tr.changed td.k::after { content: ' ●'; color: var(--amber); font-size: 9px; vertical-align: 2px; }
.vars-empty { color: var(--muted); font-size: 13px; padding: 10px 14px; }

/* ---------- SVG 元素配色 ---------- */
.vnode { fill: #33415f; stroke: #4a5b82; stroke-width: 1; }
.vnode.c-default { fill: #33415f; }
.vnode.c-compare { fill: #2c5bd4; stroke: #6d9aff; }
.vnode.c-active  { fill: #b97f2a; stroke: #ffc46b; }
.vnode.c-swap    { fill: #c2434f; stroke: #ff8c96; }
.vnode.c-sorted  { fill: #1f7a56; stroke: #46d69a; }
.vnode.c-pivot   { fill: #7a55c9; stroke: #c5a3ff; }
.vnode.c-window  { fill: #1d5f6e; stroke: #57cfe2; }
.vnode.c-muted   { fill: #232c42; stroke: #303c59; }
.vnode.c-current { fill: #b97f2a; stroke: #ffc46b; }
.vnode.c-visited { fill: #1f7a56; stroke: #46d69a; }
.vnode.c-frontier { fill: #2c5bd4; stroke: #6d9aff; }
.vnode.c-path    { fill: #7a55c9; stroke: #c5a3ff; }
.vnode.c-empty   { fill: none; stroke: #3a4665; stroke-dasharray: 4 4; }

.val-text { fill: #eef2fb; font-size: 13px; font-family: var(--mono); font-weight: 600; }
.idx-text { fill: #6d7893; font-size: 11px; font-family: var(--mono); }
.ptr-text { fill: #ffc46b; font-size: 12px; font-family: var(--mono); font-weight: 700; }
.ptr-line { stroke: #ffc46b; stroke-width: 1.6; }
.null-text { fill: #6d7893; font-size: 16px; font-family: var(--mono); }

.link-line { stroke: #5a6a92; stroke-width: 1.7; fill: none; }
.link-line.link-hl { stroke: #ffc46b; stroke-width: 2.2; }
.arrow-marker { fill: #5a6a92; }
.arrow-marker-hl { fill: #ffc46b; }

.tree-edge { stroke: #46547a; stroke-width: 1.6; }
.tree-edge.link-hl { stroke: #ffc46b; stroke-width: 2.4; }

.graph-edge { stroke: #46547a; stroke-width: 1.8; }
.graph-edge.e-active { stroke: #ffc46b; stroke-width: 2.6; }
.graph-edge.e-tree { stroke: #46d69a; stroke-width: 2.4; }
.graph-edge.e-path { stroke: #c5a3ff; stroke-width: 3; }
.wlabel-bg { fill: #0e1320; stroke: #26314d; }
.wlabel-text { fill: #aeb9d4; font-size: 11px; font-family: var(--mono); }

/* matrix */
.matrix-wrap { overflow-x: auto; padding: 4px 14px 10px; }
.matrix { border-collapse: collapse; font-family: var(--mono); font-size: 13px; margin: 0 auto; }
.matrix th {
  color: var(--muted);
  font-weight: 600;
  padding: 4px 8px;
  min-width: 34px;
  text-align: center;
}
.matrix td {
  border: 1px solid var(--border);
  min-width: 34px;
  height: 32px;
  text-align: center;
  padding: 2px 8px;
  color: #dbe2f0;
  background: #1b2438;
}
.matrix td.m-current { background: #b97f2a; color: #fff; font-weight: 700; }
.matrix td.m-ref { background: #2c5bd4; color: #fff; }
.matrix td.m-done { background: #21375e; }
.matrix td.m-path { background: #7a55c9; color: #fff; font-weight: 700; }
.matrix td.m-answer { background: #1f7a56; color: #fff; font-weight: 700; }

.footer { margin-top: 48px; color: var(--muted); font-size: 12.5px; text-align: center; }

.notfound { text-align: center; padding: 80px 0; color: var(--muted); }

/* ---------- 手機版 ---------- */
@media (max-width: 640px) {
  .topbar {
    padding: 10px 14px;
    padding-left: max(14px, env(safe-area-inset-left));
    padding-right: max(14px, env(safe-area-inset-right));
  }
  .topbar .crumb {
    flex: 1;
    min-width: 0;
    white-space: nowrap;
    overflow: hidden;
    text-overflow: ellipsis;
    font-size: 13px;
  }

  .container {
    padding: 16px 14px 56px;
    padding-left: max(14px, env(safe-area-inset-left));
    padding-right: max(14px, env(safe-area-inset-right));
  }

  .hero { margin: 8px 0 20px; }
  .hero h1 { font-size: 24px; }
  .hero p { font-size: 14px; }

  .cat-grid { grid-template-columns: 1fr 1fr; gap: 10px; }
  .cat-card { padding: 13px; border-radius: 12px; }
  .cat-card .icon { font-size: 22px; }
  .cat-card h3 { font-size: 15px; }
  .cat-card p { font-size: 12px; min-height: 0; }

  .algo-list { grid-template-columns: 1fr; }
  .page-head h1 { font-size: 21px; }
  .algo-head h1 { font-size: 20px; }
  .teach-body { padding: 0 14px 14px; }

  .viz-canvas { padding: 10px 8px 2px; min-height: 140px; }
  .note { margin: 6px 10px; font-size: 13px; }

  .seek-row { padding: 0 10px 2px; }
  .seek-row input[type='range'] { height: 30px; }

  /* 控制列改成 4 欄網格：重來/上一步/播放/下一步一排，速度與步數第二排 */
  .controls { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); padding: 8px 10px 12px; }
  .controls button { padding: 10px 2px; font-size: 13px; }
  .controls .play-btn { min-width: 0; }
  .controls select { grid-column: span 2; padding: 8px; }
  .controls .step-info { grid-column: span 2; margin-left: 0; text-align: right; align-self: center; }

  .code-scroll { max-height: 320px; }
  .code { font-size: 12.5px; }
  .vars-table td.k { width: auto; }
}

/* 觸控裝置：避免 hover 效果黏住 */
@media (hover: none) {
  .cat-card:hover { transform: none; border-color: var(--border); }
  .algo-card:hover { border-color: var(--border); }
}