:root{--bg: #0f1519;--panel: #17202a;--line: #2c3a47;--ink: #e8f0f4;--dim: #93a6b3;--accent: #5ec8c0;--accent2: #f0b357;--good: #7dd3a0;--bad: #f87171;--t0: #16202a;--t1: #1c2833;--t2: #202f3b;--t3: #182430;--given-bg: #24333f}*{box-sizing:border-box}body{margin:0;background:var(--bg);color:var(--ink);font-family:ui-sans-serif,system-ui,-apple-system,Helvetica Neue,sans-serif;line-height:1.65}main{max-width:860px;margin:0 auto;padding:2.2rem 1.2rem 4rem}header h1{font-size:2.1rem;margin:0 0 .5rem;letter-spacing:-.02em}header h1 span{color:var(--accent)}.sub{color:var(--dim);margin:0 0 1.6rem;font-size:.95rem}.sub strong{color:var(--ink)}.legend{display:flex;flex-wrap:wrap;gap:.4rem 1.4rem;color:var(--dim);font-size:.85rem;margin-bottom:1.2rem}.legend i{display:inline-flex;width:20px;height:20px;border-radius:5px;vertical-align:-5px;margin-right:6px;align-items:center;justify-content:center;font-style:normal;font-weight:700;font-size:.78rem}.legend .given-demo{background:var(--given-bg);border:2px solid var(--accent2);color:var(--ink)}.legend .num-demo{background:#5ec8c029;border:2px solid var(--accent);color:var(--accent)}.legend .blank-demo{background:transparent;border:2px solid var(--line);color:var(--dim)}#wrap{overflow-x:auto;padding-bottom:.4rem}#stage{width:fit-content;margin:0 auto}#board{background:var(--panel);border:1px solid var(--line);border-radius:12px;padding:6px;line-height:0}#board.solved{border-color:var(--good);box-shadow:0 0 0 1px var(--good),0 0 24px #7dd3a040}#board svg{display:block}.cell{stroke:#24313d;stroke-width:1;cursor:pointer}.cell.t0{fill:var(--t0)}.cell.t1{fill:var(--t1)}.cell.t2{fill:var(--t2)}.cell.t3{fill:var(--t3)}.cell.num{fill:#5ec8c026}.cell.fixed{fill:var(--given-bg);cursor:default}.cell.sel{stroke:var(--accent);stroke-width:2.5}.cell.broken{fill:#f8717138}.wall{stroke:#cddfe9;stroke-width:3;stroke-linecap:round;pointer-events:none}.frame{stroke:#cddfe9;stroke-width:3.4;fill:none;pointer-events:none}#board.solved .frame,#board.solved .wall{stroke:var(--good)}.digit{fill:var(--accent);font-weight:700;cursor:pointer;-webkit-user-select:none;user-select:none}.digit.given{fill:var(--accent2);font-weight:800;cursor:default}.digit.wrong{fill:var(--bad)}.blocked{fill:var(--line);pointer-events:none}.hud{margin:.9rem 0 .6rem;min-height:1.6em;color:var(--dim);font-size:.92rem;text-align:center}.controls{display:flex;flex-wrap:wrap;gap:.6rem 1rem;align-items:end;justify-content:center;margin-bottom:2.2rem}.controls label{display:flex;flex-direction:column;gap:.25rem;color:var(--dim);font-size:.8rem}select,button{background:var(--panel);color:var(--ink);border:1px solid var(--line);border-radius:8px;padding:.45rem .8rem;font-size:.9rem;cursor:pointer}select:hover,button:hover,button#solve{border-color:var(--accent)}.notes{border-top:1px solid var(--line);padding-top:1.4rem;color:var(--dim);font-size:.95rem}.notes h2{color:var(--ink);font-size:1.15rem;margin:1.4rem 0 .4rem}.notes p{margin:0 0 .8rem}.notes strong{color:var(--ink)}.notes em{color:var(--accent);font-style:italic}.notes table{border-collapse:collapse;font-size:.85rem;margin:0 0 1rem;width:100%}.notes th,.notes td{border:1px solid var(--line);padding:.28rem .55rem;text-align:right}.notes th:first-child,.notes td:first-child{text-align:left}.notes th{color:var(--ink);font-weight:600}footer{border-top:1px solid var(--line);margin-top:2rem;padding-top:1.2rem;color:var(--dim);font-size:.85rem}