*,*:before,*:after{box-sizing:border-box}:root{--bg: #0f0f1a;--surface: #1a1a2e;--accent: #e94560;--accent-dim: #c73e54;--text: #eaeaea;--text-muted: #a0a0a0;--cell-bg: #16213e;--cell-fixed: #1a1a2e;--cell-wrong: rgba(233, 69, 96, .35);--cell-selected: rgba(78, 205, 196, .25);--border-thin: 1px solid rgba(255, 255, 255, .15);--border-thick: 2px solid rgba(255, 255, 255, .4);--touch-min: 44px}html{font-size:16px;-webkit-tap-highlight-color:transparent}body{margin:0;min-height:100dvh;min-height:100vh;font-family:Segoe UI,system-ui,-apple-system,sans-serif;background:var(--bg);color:var(--text);overflow-x:hidden}#root{min-height:100dvh;min-height:100vh}button{font:inherit;cursor:pointer;border:none;-webkit-tap-highlight-color:transparent}button:disabled{opacity:.5;cursor:not-allowed}.app{min-height:100dvh;min-height:100vh;display:flex;flex-direction:column;padding:0}.header{padding:.75rem 1rem;background:var(--surface);border-bottom:var(--border-thin);text-align:center}.header h1{margin:0;font-size:1.5rem;font-weight:700}.main{flex:1;display:flex;flex-direction:column;align-items:center;padding:1rem;gap:1rem}.welcome{display:flex;flex-direction:column;align-items:center;gap:1.5rem;padding:2rem 1rem}.welcome p{margin:0;color:var(--text-muted)}.sudoku-wrapper{width:100%;max-width:min(90vw,360px);aspect-ratio:1}.sudoku-grid{display:grid;grid-template-columns:repeat(9,1fr);grid-template-rows:repeat(9,1fr);width:100%;height:100%;background:var(--surface);border-radius:4px;overflow:hidden}.cell{display:flex;align-items:center;justify-content:center;font-size:clamp(.875rem,4vw,1.25rem);font-weight:600;background:var(--cell-bg);border:var(--border-thin);min-height:0;aspect-ratio:1;cursor:pointer;user-select:none;-webkit-user-select:none}.cell.fixed{background:var(--cell-fixed);color:var(--text);cursor:default}.cell.wrong{background:var(--cell-wrong)}.cell.selected{background:var(--cell-selected);outline:2px solid #4ecdc4;outline-offset:-2px;z-index:1}.cell.l{border-left:var(--border-thick)}.cell.r{border-right:var(--border-thick)}.cell.t{border-top:var(--border-thick)}.cell.b{border-bottom:var(--border-thick)}.number-pad{display:grid;grid-template-columns:repeat(5,1fr);gap:.5rem;width:100%;max-width:320px}.num-btn{min-height:var(--touch-min);padding:.5rem;font-size:1.125rem;font-weight:600;background:var(--surface);color:var(--text);border:var(--border-thin);border-radius:8px}.num-btn:active{background:var(--accent-dim);color:#fff}.num-btn.clear{grid-column:span 2;font-size:.9rem;font-weight:500}.controls{width:100%;max-width:320px;display:flex;flex-direction:column;gap:1rem}.controls--compact{max-width:280px}.control-row{display:flex;flex-direction:column;gap:.35rem}.control-row label{font-size:.8rem;font-weight:600;color:var(--text-muted);text-transform:uppercase}.select{width:100%;padding:.6rem .75rem;font:inherit;font-size:1rem;background:var(--surface);color:var(--text);border:var(--border-thin);border-radius:8px;min-height:var(--touch-min)}.control-row.buttons{flex-direction:row;flex-wrap:wrap;gap:.5rem}.btn{padding:.6rem 1rem;min-height:var(--touch-min);font-size:1rem;font-weight:600;border-radius:8px}.btn-primary{background:var(--accent);color:#fff}.btn-primary:active{background:var(--accent-dim)}.btn-secondary{background:var(--surface);color:var(--text);border:var(--border-thin)}.btn-secondary:active{background:var(--cell-bg)}.footer{display:flex;justify-content:center;gap:2rem;padding:.75rem 1rem;background:var(--surface);border-top:var(--border-thin);font-size:.9rem;font-weight:600;color:var(--text-muted)}.overlay{position:fixed;top:0;right:0;bottom:0;left:0;background:#000000b3;display:flex;align-items:center;justify-content:center;z-index:10;padding:1rem}.overlay-card{background:var(--surface);border:var(--border-thin);border-radius:12px;padding:2rem;text-align:center;max-width:320px}.overlay-card h2{margin:0 0 .5rem;font-size:1.75rem;color:var(--accent)}.overlay-card p{margin:0 0 1.5rem;color:var(--text-muted)}.overlay-card .btn{width:100%}