:root{--bg: #0e1116;--panel: #181d25;--line: #2a323d;--ink: #eef3f7;--dim: #93a4b3;--accent: #6fa8dc;--cell: #222c36;--cell2: #2a3744;--given: #161d27;--sel: #20344a;--bad: #5a1f26}*{box-sizing:border-box}html,body{margin:0;height:100%}body{background:radial-gradient(900px 560px at 50% -8%,#16202a,var(--bg));color:var(--ink);font-family:system-ui,-apple-system,Segoe UI,sans-serif;display:flex;justify-content:center;-webkit-user-select:none;user-select:none}#app{width:100%;max-width:520px;padding:12px 12px 26px}header{text-align:center;margin-bottom:6px}h1{margin:0;font-size:28px;letter-spacing:6px;font-weight:800;color:var(--accent)}.sub{margin:3px 0 0;color:var(--dim);font-size:13px}.bar{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;align-items:center;margin:10px 0}.seg{display:inline-flex;background:var(--panel);border:1px solid var(--line);border-radius:999px;overflow:hidden}.seg button{background:none;border:none;color:var(--dim);padding:6px 13px;font:600 13px system-ui;cursor:pointer}.seg button.active{background:var(--accent);color:#06182b}.btn{background:var(--panel);border:1px solid var(--line);color:var(--ink);padding:7px 14px;border-radius:999px;font:700 13px system-ui;cursor:pointer}.btn:hover{border-color:var(--accent)}.btn.primary{background:var(--accent);color:#06182b;border-color:var(--accent)}.scoreboard{display:flex;gap:10px;justify-content:center;margin:8px 0}.readout{background:#0a0e13;border:1px solid var(--line);border-radius:8px;padding:5px 16px;font:800 18px ui-monospace,monospace;color:var(--accent);min-width:92px;text-align:center}.readout span{color:var(--dim);font-size:11px;display:block;font-weight:600;letter-spacing:.5px}.stage{position:relative;display:flex;justify-content:center}.board{display:grid;gap:0;width:min(94vw,440px);aspect-ratio:1;background:transparent;padding:4px}.cell{position:relative;display:flex;align-items:center;justify-content:center;font-weight:700;font-size:clamp(16px,6vw,30px);background:var(--cell);color:var(--ink);cursor:pointer;border-radius:6px;border:1px solid var(--line)}.cell:hover{background:var(--cell2)}.cell.given{background:var(--given);color:var(--accent);cursor:default;border-color:#1f2630}.cell.sel{background:var(--sel);box-shadow:inset 0 0 0 2px var(--accent)}.cell.given.sel{box-shadow:inset 0 0 0 2px var(--accent)}.cell.bad{background:var(--bad);color:#ff9aa6}.cell.bad.sel{box-shadow:inset 0 0 0 2px #ff9aa6}.pencil{display:grid;grid-template-columns:repeat(3,1fr);width:100%;height:100%;padding:2px}.pencil span{display:flex;align-items:center;justify-content:center;font-size:clamp(7px,2.4vw,11px);font-weight:600;color:var(--dim)}.gap{display:flex;align-items:center;justify-content:center}.gap.corner{background:transparent}.sign{font-weight:800;color:var(--accent);line-height:1}.sign.h,.sign.v{font-size:clamp(13px,4.2vw,22px)}.sign.bad{color:#ff7a88}.overlay{position:absolute;inset:0;display:flex;align-items:center;justify-content:center;background:#080c10c7;border-radius:8px;backdrop-filter:blur(3px)}.overlay.hidden{display:none}.card{background:var(--panel);border:1px solid var(--line);border-radius:16px;padding:22px 26px;text-align:center;max-width:320px}.card h2{margin:0 0 6px;font-size:24px;color:var(--accent)}.card p{margin:6px 0;color:var(--dim);font-size:14px}.card .row{display:flex;gap:8px;justify-content:center;margin-top:14px}.pad{display:grid;grid-template-columns:repeat(6,1fr);gap:6px;max-width:400px;margin:14px auto 0}.pad button{background:var(--panel);border:1px solid var(--line);color:var(--ink);padding:12px 0;border-radius:8px;font:800 18px ui-monospace,monospace;cursor:pointer}.pad button:hover{border-color:var(--accent)}.pad button.erase{color:var(--dim);font-size:16px}.pad button.notes-btn{font:700 13px system-ui;color:var(--dim)}.pad button.notes-btn.on{color:#06182b;background:var(--accent);border-color:var(--accent)}.pad button.hint-btn{font:700 13px system-ui;color:var(--accent)}.hint{text-align:center;color:var(--dim);font-size:12px;margin-top:12px;line-height:1.5}