:root {
    --bg: #0d1117; --panel: #161b22; --border: #30363d;
    --text: #e6edf3; --muted: #8b949e; --accent: #58a6ff;
    --green: #3fb950; --red: #f85149; --yellow: #d29922;
    --purple: #bc8cff; --orange: #ff7b47; --teal: #39d353;
    --p1:#ff6b6b;--p2:#ffd166;--p3:#06d6a0;--p4:#118ab2;
    --p5:#e040fb;--p6:#ff9800;--p7:#00bcd4;
  }
  *{box-sizing:border-box;margin:0;padding:0}
  html,body{height:100%;overflow:hidden}
  body{background:var(--bg);color:var(--text);font-family:'Segoe UI',system-ui,sans-serif;font-size:14px;line-height:1.5}
  h1{font-size:1.3rem;font-weight:700;color:var(--accent);margin-bottom:2px}
  h2{font-size:.9rem;font-weight:600;color:var(--muted);letter-spacing:.05em;text-transform:uppercase;margin-bottom:8px;margin-top:16px}
  #app{display:grid;grid-template-columns:420px 1fr;height:100vh;overflow:hidden}
  #sidebar{background:var(--panel);border-right:1px solid var(--border);padding:16px;overflow-y:auto;display:flex;flex-direction:column;gap:12px;height:100vh}
  #main{padding:16px;overflow-y:auto;display:flex;flex-direction:column;gap:16px;height:100vh}
  .card{background:var(--bg);border:1px solid var(--border);border-radius:8px;padding:12px}
  .card h2{margin-top:0}
  button{background:#21262d;border:1px solid var(--border);color:var(--text);padding:6px 12px;border-radius:6px;cursor:pointer;font-size:13px;transition:all .15s}
  button:hover{background:#30363d;border-color:var(--accent)}
  button.primary{background:var(--accent);color:#000;border-color:var(--accent);font-weight:600}
  button.primary:hover{background:#79c0ff}
  button:disabled{opacity:.4;cursor:not-allowed}
  .btn-row{display:flex;gap:6px;flex-wrap:wrap}
  label{color:var(--muted);font-size:12px;display:block;margin-bottom:3px}
  input[type=text],input[type=number]{background:#21262d;border:1px solid var(--border);color:var(--text);padding:6px 10px;border-radius:6px;font-size:13px;width:100%}
  input[type=range]{width:100%;accent-color:var(--accent)}
  .status-badge{display:inline-block;padding:2px 8px;border-radius:10px;font-size:11px;font-weight:600;text-transform:uppercase;letter-spacing:.05em}
  .s-idle{background:#21262d;color:var(--muted)}.s-ready{background:#0d2137;color:var(--accent)}
  .s-playing{background:#0d2f1a;color:var(--green)}.s-paused{background:#2d1f00;color:var(--yellow)}
  .s-done{background:#1a0a0a;color:var(--red)}
  #pseudocode{font-family:monospace;font-size:12px;background:#0d1117;border:1px solid var(--border);border-radius:6px;padding:8px;max-height:220px;overflow-y:auto}
  .pline{padding:2px 6px;border-radius:3px;cursor:pointer;white-space:pre;transition:background .15s;position:relative}
  .pline:hover::after{content:attr(data-tip);position:absolute;left:105%;top:0;background:#2d333b;border:1px solid var(--border);padding:4px 8px;border-radius:4px;font-size:11px;white-space:normal;width:200px;z-index:99;color:var(--text)}
  .pline.active{background:#0e2a4a;color:#79c0ff;font-weight:700}
  .counter-grid{display:grid;grid-template-columns:1fr 1fr;gap:6px}
  .counter-item{background:#21262d;border-radius:6px;padding:8px;text-align:center}
  .counter-item .val{font-size:1.4rem;font-weight:700;color:var(--accent)}
  .counter-item .lbl{font-size:10px;color:var(--muted);text-transform:uppercase}
  #stepbox{background:#0d2137;border:1px solid #1f4070;border-radius:6px;padding:10px;min-height:48px;font-size:13px;line-height:1.5;color:var(--text)}
  #historytable{width:100%;border-collapse:collapse;font-size:11px}
  #historytable th{background:#21262d;padding:4px 8px;text-align:left;color:var(--muted);position:sticky;top:0}
  #historytable td{padding:3px 8px;border-bottom:1px solid var(--border);cursor:pointer}
  #historytable tr:hover td{background:#21262d}
  #historytable tr.cur td{background:#0e2a4a}
  .hist-wrap{max-height:160px;overflow-y:auto;border:1px solid var(--border);border-radius:6px}
  #vizarea{min-height:340px;position:relative}
  svg text{dominant-baseline:middle;text-anchor:middle;font-family:'Segoe UI',sans-serif}
  .matrix-cell{transition:all .25s}
  .legend-row{display:flex;flex-wrap:wrap;gap:8px;margin-bottom:8px}
  .legend-item{display:flex;align-items:center;gap:4px;font-size:11px}
  .legend-dot{width:12px;height:12px;border-radius:3px}
  details{border:1px solid var(--border);border-radius:6px;overflow:hidden}
  summary{padding:8px 12px;cursor:pointer;background:#21262d;font-weight:600;font-size:13px;list-style:none;user-select:none}
  summary:hover{background:#30363d}
  details[open] summary{border-bottom:1px solid var(--border)}
  .details-body{padding:12px;line-height:1.7;color:var(--muted);font-size:13px}
  .concept-box{border-left:3px solid var(--accent);background:#0d2137;padding:8px 12px;border-radius:0 6px 6px 0;margin:6px 0;font-size:12px}
  .warn-box{border-left:3px solid var(--yellow);background:#1f1700;padding:8px 12px;border-radius:0 6px 6px 0;margin:6px 0;font-size:12px}
  #charttabs{display:flex;gap:4px;margin-bottom:8px}
  #charttabs button{font-size:11px;padding:4px 10px}
  #charttabs button.active{background:var(--accent);color:#000}
  .tab-panel{display:none}.tab-panel.active{display:block}
  canvas{background:#0d1117;border-radius:6px;border:1px solid var(--border)}
  .preset-row{display:flex;gap:6px;flex-wrap:wrap}
  .preset-btn{font-size:11px;padding:4px 8px}
  #matinput{display:grid;grid-template-columns:1fr 1fr;gap:8px}
  .mat-input-block label{font-size:11px;margin-bottom:4px;display:block;color:var(--muted)}
  .mat-input-block textarea{background:#21262d;border:1px solid var(--border);color:var(--text);padding:6px;border-radius:6px;font-size:12px;width:100%;font-family:monospace;resize:vertical;min-height:80px}
  #recursion-svg-wrap{overflow:auto;max-height:400px;border:1px solid var(--border);border-radius:6px;background:#0d1117}
  @media(max-width:979px){html,body{overflow:auto}#app{grid-template-columns:1fr;height:auto;overflow:visible}#sidebar{height:auto;border-right:none;border-bottom:1px solid var(--border)}#main{height:auto}}
  .p1c{fill:var(--p1)}.p2c{fill:var(--p2)}.p3c{fill:var(--p3)}.p4c{fill:var(--p4)}.p5c{fill:var(--p5)}.p6c{fill:var(--p6)}.p7c{fill:var(--p7)}
  .subtag{font-size:9px;font-family:monospace}
  #section-tabs{display:flex;gap:4px;flex-wrap:wrap;margin-bottom:12px}
  #section-tabs button{font-size:12px;padding:5px 12px}
  #section-tabs button.active{background:var(--accent);color:#000;border-color:var(--accent)}
  .section-panel{display:none}.section-panel.active{display:flex;flex-direction:column;gap:16px}
  #controls-card {position: sticky;top: 0;z-index: 50;background: var(--panel);padding-top: 8px;padding-bottom: 8px;}