:root {
      color-scheme: light dark;
      --bg: #f3f5f1;
      --panel: #ffffff;
      --panel-soft: #f8faf7;
      --text: #17211b;
      --muted: #657168;
      --border: #d5ddd7;
      --accent: #217346;
      --accent-strong: #145c35;
      --accent-soft: #dff0e5;
      --accent-faint: #edf7f0;
      --danger: #a9463d;
      --warning: #a36b18;
      --ground: #3f4842;
      --branch: #126b31;
      --pebble: #78847b;
      --shadow: 0 8px 24px rgba(26, 43, 33, .08);
      --move-flash-step: .28s;
      --fall-duration: .75s;
      --site-surface: var(--panel);
      --site-soft: var(--panel-soft);
      --site-text: var(--text);
      --site-muted: var(--muted);
      --site-border: var(--border);
      --site-accent: var(--accent);
      --site-accent-strong: var(--accent-strong);
    }

    @media (prefers-color-scheme: dark) {
      :root:not([data-theme="light"]) {
        color-scheme: dark;
        --bg: #0f1511;
        --panel: #151d18;
        --panel-soft: #19231c;
        --text: #eef5f0;
        --muted: #a6b4aa;
        --border: #33423a;
        --accent: #65bd82;
        --accent-strong: #82d09c;
        --accent-soft: #203a29;
        --accent-faint: #192b20;
        --danger: #ef8e84;
        --warning: #e3b361;
        --ground: #a6b0a9;
        --branch: #61bf7e;
        --pebble: #a1ada5;
        --shadow: 0 10px 28px rgba(0, 0, 0, .22);
      }
    }

    :root[data-theme="dark"] {
      color-scheme: dark;
      --bg: #0f1511;
      --panel: #151d18;
      --panel-soft: #19231c;
      --text: #eef5f0;
      --muted: #a6b4aa;
      --border: #33423a;
      --accent: #65bd82;
      --accent-strong: #82d09c;
      --accent-soft: #203a29;
      --accent-faint: #192b20;
      --danger: #ef8e84;
      --warning: #e3b361;
      --ground: #a6b0a9;
      --branch: #61bf7e;
      --pebble: #a1ada5;
      --shadow: 0 10px 28px rgba(0, 0, 0, .22);
    }

    :root[data-theme="light"] { color-scheme: light; }

    * { box-sizing: border-box; }

    body {
      margin: 0;
      background: var(--bg);
      color: var(--text);
      font-family: Inter, ui-sans-serif, system-ui, -apple-system, BlinkMacSystemFont, "Segoe UI", sans-serif;
      line-height: 1.45;
    }

    button, input, select, textarea { font: inherit; color: inherit; }
    button { cursor: pointer; }
    button:disabled { cursor: not-allowed; opacity: .45; }

    .site-header {
      position: sticky;
      top: 0;
      z-index: 60;
      border-bottom: 1px solid var(--site-border);
      background: color-mix(in srgb, var(--site-surface) 92%, transparent);
      backdrop-filter: blur(12px);
    }
    .site-bar {
      width: min(1180px, calc(100% - 24px));
      margin: 0 auto;
      min-height: 58px;
      display: flex;
      align-items: center;
      gap: 10px;
      padding: 8px 0;
    }
    .site-brand {
      display: inline-flex;
      align-items: center;
      gap: 9px;
      margin-right: auto;
      color: var(--site-text);
      font-weight: 800;
      text-decoration: none;
      white-space: nowrap;
    }
    .site-mark {
      display: grid;
      place-items: center;
      width: 32px;
      height: 32px;
      border-radius: 10px;
      background: var(--site-accent);
      color: white;
    }
    .site-nav { display: flex; align-items: center; flex-wrap: wrap; gap: 4px; }
    .site-link {
      border-radius: 9px;
      padding: 7px 9px;
      color: var(--site-muted);
      font-size: .88rem;
      font-weight: 700;
      text-decoration: none;
    }
    .site-link:hover { background: var(--site-soft); color: var(--site-text); }
    .site-link.active { background: var(--site-accent); color: white; }
    .site-version { color: var(--site-muted); font-size: .8rem; font-weight: 750; white-space: nowrap; }
    .site-theme {
      display: flex;
      align-items: center;
      gap: 6px;
      border: 1px solid var(--site-border);
      border-radius: 10px;
      background: var(--site-surface);
      padding: 3px 5px 3px 8px;
      white-space: nowrap;
    }
    .site-theme > span { margin: 0; color: var(--site-muted); font-size: .8rem; font-weight: 700; }
    .site-theme select { width: auto; border: 0; background: transparent; color: var(--site-text); padding: 4px 18px 4px 3px; }
    .site-footer {
      width: min(1180px, calc(100% - 24px));
      margin: 0 auto 34px;
      padding: 18px 8px 0;
      border-top: 1px solid var(--site-border);
      display: flex;
      align-items: center;
      justify-content: center;
      flex-wrap: wrap;
      gap: 8px 14px;
      color: var(--site-muted);
      text-align: center;
      font-size: .88rem;
    }
    .site-footer nav { display: flex; justify-content: center; flex-wrap: wrap; gap: 8px 12px; }
    .site-footer a { color: var(--site-accent-strong); font-weight: 700; text-decoration: none; }
    .site-footer a:hover { text-decoration: underline; }
    @media (max-width: 860px) {
      .site-bar { flex-wrap: wrap; }
      .site-nav { order: 3; width: 100%; }
    }
    @media (max-width: 560px) {
      .site-brand span:last-child { font-size: .92rem; }
      .site-version { display: none; }
      .site-link { padding: 6px 7px; font-size: .82rem; }
      .site-theme > span { display: none; }
    }

    .app {
      width: min(1180px, calc(100% - 24px));
      margin: 0 auto;
      padding: 22px 0 48px;
    }

    .app-header {
      display: flex;
      align-items: end;
      justify-content: space-between;
      gap: 18px;
      margin-bottom: 16px;
    }

    .app-header h1 { margin: 0; font-size: clamp(1.5rem, 4vw, 2.25rem); }
    .app-header p { margin: 4px 0 0; color: var(--muted); }

    .header-actions { display: flex; align-items: end; justify-content: flex-end; flex-wrap: wrap; gap: 9px; }
    .version-pill { align-self: center; border: 1px solid var(--border); border-radius: 999px; background: var(--panel); color: var(--muted); padding: 7px 10px; box-shadow: var(--shadow); font-size: .82rem; font-weight: 700; }
    .theme-control { display: flex; align-items: center; gap: 7px; border: 1px solid var(--border); border-radius: 12px; background: var(--panel); padding: 4px 5px 4px 10px; box-shadow: var(--shadow); }
    .theme-control > span { margin: 0; color: var(--muted); font-size: .82rem; font-weight: 650; }
    .theme-control select { width: auto; border: 0; background: transparent; padding: 4px 22px 4px 4px; }

    .tabs { display: inline-flex; gap: 4px; padding: 4px; border: 1px solid var(--border); border-radius: 12px; background: var(--panel); box-shadow: var(--shadow); }
    .tab { border: 0; border-radius: 9px; padding: 8px 14px; background: transparent; }
    .tab.active { background: var(--accent); color: white; font-weight: 650; }
    .panel { border: 1px solid var(--border); border-radius: 16px; background: var(--panel); box-shadow: var(--shadow); }
    .setup-panel { margin-bottom: 16px; }
    .setup-panel > summary { display: flex; align-items: center; justify-content: space-between; gap: 12px; padding: 13px 16px; cursor: pointer; list-style: none; font-weight: 650; }
    .setup-panel > summary::-webkit-details-marker { display: none; }
    .setup-panel > summary::after { content: "▾"; color: var(--muted); }
    .setup-panel[open] > summary::after { transform: rotate(180deg); }
    .setup-body { border-top: 1px solid var(--border); padding: 16px; }
    .setup-grid { display: grid; grid-template-columns: minmax(0, 1.15fr) minmax(280px, .85fr); gap: 18px; }
    .section-title { margin: 0 0 9px; font-size: 1rem; }
    .help { color: var(--muted); font-size: .9rem; }
    textarea, input[type="number"], select { width: 100%; border: 1px solid var(--border); border-radius: 10px; background: var(--panel-soft); padding: 9px 10px; }
    textarea { min-height: 178px; resize: vertical; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; font-size: .88rem; }
    .button-row { display: flex; flex-wrap: wrap; align-items: center; gap: 9px; }
    .button { border: 1px solid var(--border); border-radius: 10px; background: var(--panel-soft); padding: 8px 12px; }
    .button:hover:not(:disabled) { border-color: var(--accent); }
    .button.primary { background: var(--accent); color: white; border-color: var(--accent); font-weight: 650; }
    .button.danger { color: var(--danger); }
    .random-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 10px; margin-bottom: 12px; }
    label > span { display: block; margin-bottom: 4px; color: var(--muted); font-size: .86rem; }
    .view { display: none; }
    .view.active { display: block; }
    .play-toolbar { display: grid; grid-template-columns: minmax(180px, 240px) minmax(220px, 1fr) auto; align-items: end; gap: 12px; padding: 14px 16px; margin-bottom: 12px; }
    .toolbar-buttons { display: flex; justify-content: flex-end; flex-wrap: wrap; gap: 8px; }
    .speed-control { min-width: 0; }
    .speed-row { display: flex; align-items: center; gap: 10px; }
    .speed-row input { flex: 1; min-width: 120px; }
    .speed-value { min-width: 86px; text-align: right; color: var(--text); font-size: .86rem; font-variant-numeric: tabular-nums; }
    .turn-banner { position: relative; overflow: hidden; margin-bottom: 12px; padding: 15px 18px; border: 2px solid var(--accent); border-radius: 15px; background: var(--accent-faint); }
    .turn-banner h2 { margin: 0; font-size: 1.25rem; }
    .turn-banner p { margin: 3px 0 0; color: var(--muted); }
    .turn-banner.computer { border-color: var(--warning); }
    .turn-banner.computer::after { content: ""; position: absolute; inset: 0; background: linear-gradient(90deg, transparent, rgba(255,255,255,.16), transparent); transform: translateX(-100%); animation: thinkingSweep 1.4s linear infinite; pointer-events: none; }
    .turn-banner.finished { border-color: var(--muted); }
    @keyframes thinkingSweep { to { transform: translateX(100%); } }
    .garden-panel { padding: 12px 12px 6px; }
    .garden-head { display: flex; justify-content: space-between; align-items: center; gap: 12px; padding: 0 5px 8px; }
    .garden-head strong { font-size: 1rem; }
    .garden-head code { color: var(--muted); }
    #garden-svg, #explain-garden-svg { display: block; width: 100%; height: auto; min-height: 260px; border-radius: 12px; background: linear-gradient(to bottom, color-mix(in srgb, var(--accent-faint) 30%, transparent), transparent 68%), var(--panel-soft); }
    .ground-line { stroke: var(--ground); stroke-width: 5; stroke-linecap: round; }
    .ground-hatch { stroke: var(--ground); stroke-width: 2; opacity: .5; }
    .branch { stroke: var(--branch); stroke-width: 8; stroke-linecap: round; cursor: pointer; transition: stroke-width .13s ease, opacity .13s ease; }
    .branch.playable:hover { stroke-width: 12; }
    .joint { fill: var(--branch); }
    .component-label { fill: var(--text); font-size: 15px; text-anchor: middle; font-weight: 650; }
    .component-value { fill: var(--muted); font-size: 12px; text-anchor: middle; }
    .pot-body { fill: var(--accent-soft); stroke: var(--ground); stroke-width: 3; cursor: pointer; }
    .pot-rim { fill: var(--panel); stroke: var(--ground); stroke-width: 3; cursor: pointer; }
    .pebble { fill: var(--pebble); stroke: var(--panel); stroke-width: 1; pointer-events: none; }
    .pot-count { fill: var(--text); text-anchor: middle; font-weight: 700; font-size: 18px; pointer-events: none; }
    .pot-group.playable:hover .pot-body, .pot-group.playable:hover .pot-rim { stroke: var(--accent); stroke-width: 5; }
    .move-pending { stroke: var(--warning) !important; animation: moveFlash var(--move-flash-step) ease-in-out 4 alternate; }
    .pot-group.move-pending { animation: potFlash var(--move-flash-step) ease-in-out 4 alternate; transform-box: fill-box; transform-origin: center; }
    @keyframes moveFlash { from { opacity: .25; stroke-width: 7; } to { opacity: 1; stroke-width: 15; } }
    @keyframes potFlash { from { opacity: .35; transform: scale(.96); } to { opacity: 1; transform: scale(1.05); } }
    .recent-gone { stroke: var(--danger) !important; pointer-events: none; transform-box: fill-box; transform-origin: center; animation: fallAway var(--fall-duration) ease-in forwards; }
    @keyframes fallAway { 0% { opacity: 1; transform: translateY(0) rotate(0deg); } 100% { opacity: 0; transform: translateY(38px) rotate(8deg); } }
    .move-panel { display: grid; gap: 8px; margin-top: 10px; padding: 10px 12px; border-top: 1px solid var(--border); }
    .heap-control { display: grid; grid-template-columns: minmax(120px, 1fr) minmax(110px, 180px) auto; gap: 9px; align-items: end; }
    .dashboard { display: grid; grid-template-columns: repeat(4, minmax(0, 1fr)); gap: 10px; margin: 12px 0; }
    .metric { border: 1px solid var(--border); border-radius: 12px; background: var(--panel); padding: 11px 12px; }
    .metric-label { color: var(--muted); font-size: .82rem; }
    .metric-value { font-size: 1.35rem; font-weight: 700; margin-top: 2px; }
    .lower-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 12px; margin-top: 12px; }
    .lower-grid .panel { padding: 14px 16px; }
    .lower-grid h3 { margin: 0 0 8px; font-size: 1rem; }
    .explanation-text p { margin: 0 0 8px; }
    .move-log { margin: 0; padding: 0; list-style: none; max-height: 270px; overflow: auto; }
    .move-log li { padding: 9px 0; border-top: 1px solid var(--border); }
    .move-log li:first-child { border-top: 0; }
    .move-log small { color: var(--muted); }
    .explain-summary { display: grid; grid-template-columns: minmax(0, 1.25fr) minmax(260px, .75fr); gap: 12px; margin-bottom: 12px; }
    .callout { padding: 16px; }
    .callout h2 { margin: 0 0 5px; }
    .callout p { margin: 5px 0; }
    .winner { border-left: 5px solid var(--accent); }
    .analysis-grid { display: grid; grid-template-columns: repeat(2, minmax(0, 1fr)); gap: 12px; margin-bottom: 12px; }
    .analysis-card { padding: 14px 16px; }
    .analysis-card h3 { margin: 0 0 8px; }
    .option-list { margin: 8px 0 0; padding-left: 20px; }
    .option-list li { margin: 4px 0; }
    .xor-table { width: 100%; border-collapse: collapse; font-family: ui-monospace, SFMono-Regular, Menlo, Consolas, monospace; }
    .xor-table th, .xor-table td { padding: 7px 9px; border-bottom: 1px solid var(--border); text-align: left; }
    .xor-table th { color: var(--muted); font-family: inherit; font-size: .82rem; }
    .theory { padding: 15px 17px; }
    .theory-intro { margin-bottom: 12px; }
    .theory-intro > h2 { margin: 0 0 6px; }
    .theory-intro > p { margin: 6px 0; }
    .theory-steps { display: grid; grid-template-columns: repeat(auto-fit, minmax(178px, 1fr)); gap: 10px; margin: 14px 0; }
    .theory-step { border: 1px solid var(--border); border-radius: 12px; background: var(--panel-soft); padding: 12px; }
    .theory-step strong { display: block; margin-bottom: 5px; }
    .step-number { display: inline-grid; place-items: center; width: 24px; height: 24px; margin-right: 6px; border-radius: 999px; background: var(--accent); color: white; font-size: .8rem; }
    .application-strip { border-left: 4px solid var(--accent); border-radius: 10px; background: var(--accent-faint); padding: 11px 13px; }
    .balance-strip { margin-top: 10px; border: 1px solid var(--border); border-radius: 10px; background: var(--panel); padding: 11px 13px; }
    .guide-link-strip { margin-top: 12px; display: flex; align-items: center; justify-content: space-between; gap: 14px; border: 1px solid var(--border); border-radius: 12px; background: var(--panel-soft); padding: 13px 14px; }
    .guide-link-strip span { color: var(--muted); }
    .guide-link-strip .button { flex: 0 0 auto; text-decoration: none; }
    .theory h3 { margin: 0 0 8px; }
    .theory p { margin: 7px 0; }
    .theory code { color: var(--accent-strong); }
    .status-note { color: var(--muted); font-size: .9rem; }
    .hidden { display: none !important; }
    .app-footer { margin-top: 18px; padding: 15px 4px 0; border-top: 1px solid var(--border); color: var(--muted); text-align: center; font-size: .84rem; }
    .app-footer a { color: var(--accent-strong); font-weight: 650; }

    @media (max-width: 820px) {
      .app-header { align-items: stretch; flex-direction: column; }
      .guide-link-strip { align-items: flex-start; flex-direction: column; }
      .tabs { align-self: flex-start; }
      .setup-grid, .explain-summary, .lower-grid { grid-template-columns: 1fr; }
      .play-toolbar { grid-template-columns: 1fr; }
      .toolbar-buttons { justify-content: flex-start; }
      .dashboard { grid-template-columns: repeat(2, minmax(0, 1fr)); }
      .analysis-grid { grid-template-columns: 1fr; }
      .term-grid { grid-template-columns: 1fr; }
    }

    @media (max-width: 520px) {
      .app { width: min(100% - 12px, 1180px); padding-top: 10px; }
      .random-grid { grid-template-columns: 1fr; }
      .heap-control { grid-template-columns: 1fr; }
      .dashboard { grid-template-columns: 1fr 1fr; }
      .button { padding: 8px 10px; }
    }