:root{--bg:#f8fafc;--surface:#fff;--text:#0f172a;--muted:#64748b;--border:#e2e8f0;--cell:#f1f5f9;--cell-locked:#dbeafe;--pipe:#94a3b8;--pipe-connected:#0284c7;--pipe-solved:#16a34a;--accent:#0284c7;--lightningcss-light:initial;--lightningcss-dark: ;color-scheme:light dark;font-family:system-ui,-apple-system,Segoe UI,Roboto,sans-serif}@media (prefers-color-scheme:dark){:root{--lightningcss-light: ;--lightningcss-dark:initial;--bg:#0f172a;--surface:#1e293b;--text:#f1f5f9;--muted:#94a3b8;--border:#334155;--cell:#1e293b;--cell-locked:#1e3a5f;--pipe:#64748b;--pipe-connected:#38bdf8;--pipe-solved:#4ade80;--accent:#38bdf8}}*{box-sizing:border-box}body{background:var(--bg);color:var(--text);margin:0}.app{flex-direction:column;gap:16px;max-width:640px;margin:0 auto;padding:16px;display:flex}.header{text-align:center}.header h1{margin:0;font-size:1.75rem}.date{color:var(--muted);margin:4px 0 0}button{font:inherit;color:inherit;background:var(--surface);border:1px solid var(--border);cursor:pointer;border-radius:8px;padding:8px 14px}button:hover{border-color:var(--accent)}.stats{color:var(--muted);font-variant-numeric:tabular-nums;justify-content:center;gap:24px;display:flex}@media (width<=420px){.stats{gap:16px}}.stats strong{color:var(--text)}.board-wrap{justify-content:center;display:flex}.board{background:var(--border);touch-action:manipulation;-webkit-user-select:none;user-select:none;-webkit-touch-callout:none;border-radius:8px;width:min(100%,560px);height:auto}.tile{cursor:pointer;outline:none}.cell{fill:var(--cell);stroke:var(--border);stroke-width:.03px}.tile.locked .cell{fill:var(--cell-locked)}.tile:focus-visible .cell{stroke:var(--accent);stroke-width:.08px}.pipe{transform-box:fill-box;transform-origin:50%;transition:transform .12s ease-out}.hitbox{fill:none}.segment{stroke:var(--pipe);stroke-width:.2px;stroke-linecap:butt}.hub,.endpoint,.source{fill:var(--pipe)}.endpoint{fill:var(--cell);stroke:var(--pipe);stroke-width:.08px}.tile.connected .segment{stroke:var(--pipe-connected)}.tile.connected .hub,.tile.connected .source{fill:var(--pipe-connected)}.tile.connected .endpoint{stroke:var(--pipe-connected)}.board.solved .segment{stroke:var(--pipe-solved)}.board.solved .hub,.board.solved .source{fill:var(--pipe-solved)}.board.solved .endpoint{stroke:var(--pipe-solved)}.board.solved .tile{cursor:default}.solved-banner{text-align:center;background:var(--surface);border:1px solid var(--pipe-solved);border-radius:8px;padding:12px}.solved-banner p{margin:0 0 8px;font-weight:600}.controls{justify-content:center;display:flex}.help{color:var(--muted);line-height:1.5}.help summary{cursor:pointer;color:var(--text)}@media (prefers-reduced-motion:reduce){.pipe{transition:none}}