:root{--bg: #0f1117;--surface: #1a1d27;--border: #2a2f3d;--text: #e8eaef;--muted: #8b93a7;--primary: #5b8def;--accent: #3ecf8e;--danger: #ef6b6b;--radius: 10px}*{box-sizing:border-box}body{margin:0;font-family:Segoe UI,system-ui,-apple-system,sans-serif;background:var(--bg);color:var(--text);min-height:100vh}.app{max-width:1200px;margin:0 auto;padding:24px 20px 40px}.header{display:grid;grid-template-columns:1.1fr 1fr;gap:20px 28px;align-items:start;margin-bottom:4px}.header h1{margin:0 0 8px;font-size:1.75rem;font-weight:600}.subtitle{margin:0;color:var(--muted);font-size:.95rem;line-height:1.55;max-width:36em}.header-guide{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:14px 16px}.header-guide h2{margin:0 0 8px;font-size:.95rem;font-weight:600;color:var(--text)}.header-guide ol{margin:0;padding-left:1.2em;color:var(--muted);font-size:.88rem;line-height:1.65}.header-guide li{margin-bottom:2px}.guide-note{margin:10px 0 0;font-size:.8rem;line-height:1.5;color:#a8b0c2}@media(max-width:720px){.header{grid-template-columns:1fr;gap:14px}}.toolbar{display:flex;flex-wrap:wrap;gap:10px;align-items:center;margin:24px 0;padding:16px;background:var(--surface);border:1px solid var(--border);border-radius:var(--radius)}.btn{padding:8px 14px;border:1px solid var(--border);border-radius:8px;background:#252936;color:var(--text);font-size:.875rem;cursor:pointer;transition:background .15s,border-color .15s}.btn:hover:not(:disabled){background:#2f3545;border-color:#3d4558}.btn:disabled{opacity:.45;cursor:not-allowed}.btn-primary{background:var(--primary);border-color:var(--primary);color:#fff}.btn-primary:hover:not(:disabled){background:#4a7de0}.btn-accent{background:var(--accent);border-color:var(--accent);color:#0f1117;font-weight:600}.btn-accent:hover:not(:disabled){background:#35b87d}.btn-ghost{background:transparent}.btn-secondary{background:#2a2f3d;border-color:#3d4558;color:#c5cad6;font-size:.8rem}.btn-secondary:hover:not(:disabled){background:#343b4d;border-color:#4a5368}.toolbar-sep{display:inline-block;width:1px;height:28px;background:var(--border);margin:0 4px}.btn.active{outline:2px solid var(--primary);outline-offset:1px}#btnDownload:not(:disabled){background:#f4b6c2;border-color:#f4b6c2;color:#3a1f28;font-weight:600}#btnDownload:not(:disabled):hover{background:#f7c5ce;border-color:#f7c5ce}.control{display:flex;align-items:center;gap:8px;font-size:.95rem;color:var(--muted)}.control input[type=range]{-webkit-appearance:none;appearance:none;width:96px;height:16px;background:transparent;padding:0;margin:0;cursor:pointer}.control input[type=range]::-webkit-slider-runnable-track{height:5px;border-radius:999px;background:#fff}.control input[type=range]::-webkit-slider-thumb{-webkit-appearance:none;appearance:none;width:13px;height:13px;margin-top:-4px;border-radius:50%;background:var(--primary);border:none;box-shadow:none}.control input[type=range]::-moz-range-track{height:5px;border-radius:999px;background:#fff;border:none}.control input[type=range]::-moz-range-thumb{width:13px;height:13px;border-radius:50%;background:var(--primary);border:none;box-shadow:none}.canvas-area{display:grid;grid-template-columns:1fr 1fr;gap:16px}.auto-label-short{display:none}@media(max-width:860px){.canvas-area{grid-template-columns:1fr}}@media(max-width:720px){.app{padding:14px 12px 28px}.header h1{font-size:1.35rem}.subtitle{font-size:.85rem;line-height:1.4}.toolbar{gap:8px;padding:12px;margin:16px 0}.toolbar-sep{display:none}.toolbar>.btn,.toolbar>label.btn{flex:1 1 calc(50% - 8px);min-height:44px;padding:10px 12px;display:inline-flex;align-items:center;justify-content:center;text-align:center;-webkit-tap-highlight-color:transparent}.toolbar>label.btn-primary,.toolbar>#btnProcess,.toolbar>#btnDownload,.toolbar>#btnReset,.toolbar>#btnAuto{flex:1 1 100%}.auto-label-full{display:none}.auto-label-short{display:inline}.control{flex:1 1 100%;justify-content:space-between;min-height:40px}.control input[type=range]{flex:1;width:auto;min-width:0;max-width:none;height:28px}.control input[type=range]::-webkit-slider-thumb{width:18px;height:18px;margin-top:-6.5px}.control input[type=range]::-moz-range-thumb{width:18px;height:18px}.panel{padding:12px}.canvas-wrap{max-height:58vh;min-height:180px}.hint,.status{font-size:.8rem;line-height:1.45}}.panel{background:var(--surface);border:1px solid var(--border);border-radius:var(--radius);padding:14px}.panel h2{margin:0 0 12px;font-size:.95rem;font-weight:500;color:var(--muted)}.canvas-wrap{position:relative;background:#12151c;border-radius:8px;overflow:auto;max-height:70vh;min-height:200px;display:flex;justify-content:center;align-items:flex-start}.canvas-stage{position:relative;display:inline-block;max-width:100%;line-height:0}.canvas-stage>canvas{display:block;max-width:100%;height:auto}.mask-layer{position:absolute;left:0;top:0;width:100%;height:100%;pointer-events:none;opacity:.55;touch-action:none}.canvas-wrap.drawing .mask-layer{pointer-events:auto;cursor:crosshair}canvas{display:block;max-width:100%;height:auto}.hint,.status{margin:10px 0 0;font-size:.82rem;color:var(--muted)}.status.ok{color:var(--accent)}.status.err{color:var(--danger)}.empty-placeholder{padding:60px 20px;text-align:center;color:var(--muted);font-size:.9rem}