:root{--bg:#f4f3ef;--surface:#fffdf9;--ink:#1e2420;--muted:#69716c;--line:#d7d9d1;--strong-line:#8e9991;--accent:#2f6f5e;--accent-soft:#e3efe8;--danger:#b94a42;--shadow:0 18px 45px rgba(31,42,35,.08)}*{box-sizing:border-box}body{margin:0;min-width:320px;background:var(--bg);color:var(--ink);font-family:Inter,Noto Sans SC,system-ui,sans-serif;transition:background .2s,color .2s}body.dark-page{--bg:#1c2420;--surface:#27312c;--ink:#eef4ee;--muted:#a9b5ac;--line:#435047;--strong-line:#718178;--accent:#8bd0af;--accent-soft:#315347;--danger:#f08d83;--shadow:0 18px 45px rgba(0,0,0,.2)}button{font:inherit;color:inherit;cursor:pointer}.app-shell{width:min(1080px,calc(100% - 32px));margin:0 auto;padding:36px 0 24px}.topbar{display:flex;justify-content:space-between;align-items:flex-start;margin-bottom:28px}.eyebrow,.label{color:var(--muted);font-size:11px;font-weight:700;letter-spacing:.08em;text-transform:uppercase}.eyebrow{margin:0 0 6px}h1{margin:0;font-size:clamp(28px,5vw,42px);line-height:1.1}.icon-button{width:40px;height:40px;border:1px solid var(--line);background:var(--surface);border-radius:8px;font-size:20px}.game-layout{display:grid;grid-template-columns:minmax(0,1fr) 280px;gap:24px;align-items:start}.board-panel,.side-panel{background:var(--surface);border:1px solid var(--line);border-radius:8px;box-shadow:var(--shadow)}.board-panel{padding:clamp(16px,3vw,30px)}.board-head{display:grid;grid-template-columns:auto minmax(0,1fr) auto;gap:12px;align-items:end;margin-bottom:18px}.difficulty-display{min-width:0}.board-head strong{display:block;margin-top:3px;font-size:18px}.timer{color:var(--accent);font-variant-numeric:tabular-nums;font-size:22px;font-weight:700;white-space:nowrap}.quick-actions{display:flex;justify-content:center;gap:5px;min-width:0}.quick-action{width:32px;height:32px;flex:0 0 32px;display:grid;place-items:center;padding:0;border:1px solid var(--line);border-radius:6px;background:transparent;color:var(--muted);font-size:16px}.quick-action:hover,.quick-action.active{border-color:var(--accent);background:var(--accent-soft);color:var(--accent)}.board{width:min(100%,560px);aspect-ratio:1;margin:0 auto;display:grid;grid-template-columns:repeat(9,1fr);grid-template-rows:repeat(9,1fr);border:2px solid var(--strong-line);background:var(--strong-line);gap:1px}.cell{position:relative;display:grid;place-items:center;min-width:0;border:0;background:var(--surface);font-size:clamp(20px,5vw,32px);font-weight:650}.cell:nth-child(3n){border-right:2px solid var(--strong-line)}.cell:nth-child(9n){border-right:0}.cell:nth-child(n+19):nth-child(-n+27),.cell:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid var(--strong-line)}.cell.given{color:var(--ink);background:#f0f2ed}.cell.editable{color:var(--accent)}.cell.selected{background:#a7d0bc;box-shadow:inset 0 0 0 2px var(--accent);z-index:1}.cell.related{background:#d5e8db}.cell.conflict{color:var(--danger);background:#fbeae7}.cell-value{line-height:1}.notes{position:absolute;inset:4px;display:grid;grid-template-columns:repeat(3,1fr);grid-template-rows:repeat(3,1fr);align-items:center;justify-items:center;color:var(--muted);font-size:clamp(8px,1.4vw,11px);font-weight:600;line-height:1}.notes span{visibility:hidden}.notes span.visible{visibility:visible}.status{min-height:22px;margin:14px 0;color:var(--muted);text-align:center;font-size:13px}.status.error{color:var(--danger)}.status.success{color:var(--accent)}.number-pad{display:grid;grid-template-columns:repeat(5,1fr);gap:8px;max-width:560px;margin:0 auto}.number-pad button,.difficulty-tabs button,.action-button{border:1px solid var(--line);background:transparent;border-radius:6px;min-height:42px}.number-pad button{font-size:18px;font-weight:650}.number-pad button:hover,.difficulty-tabs button:hover,.action-button:hover{border-color:var(--accent);color:var(--accent)}.number-pad .erase{grid-column:span 2;color:var(--muted);font-size:13px;font-weight:600}.side-panel{padding:22px}.control-section+.control-section,.stats-section{border-top:1px solid var(--line);margin-top:22px;padding-top:22px}.difficulty-tabs{display:grid;grid-template-columns:repeat(2,1fr);gap:7px;margin:12px 0}.source-select{display:grid;gap:7px;margin-top:12px;color:var(--muted);font-size:12px}.source-select select{width:100%;min-height:38px;padding:0 10px;border:1px solid var(--line);border-radius:6px;background:var(--surface);color:var(--ink);font:inherit}.source-select select:focus{outline:2px solid var(--accent-soft);border-color:var(--accent)}.difficulty-tabs button{min-height:36px;font-size:13px}.difficulty-tabs button.active{border-color:var(--accent);background:var(--accent);color:#fff}.primary-button{width:100%;min-height:45px;border:0;border-radius:6px;background:var(--ink);color:#fff;font-weight:700}.primary-button span{margin-left:8px}.actions{display:grid;gap:8px}.action-button{display:flex;justify-content:flex-start;align-items:center;gap:10px;padding:0 12px;text-align:left}.action-button span{width:18px;color:var(--accent);text-align:center;font-size:17px}.action-button.active{border-color:var(--accent);background:var(--accent-soft);color:var(--accent)}.stat-row{display:flex;justify-content:space-between;margin-top:14px;color:var(--muted);font-size:13px}.stat-row strong{color:var(--ink);font-variant-numeric:tabular-nums}.source-note{margin-top:16px;color:var(--muted);font-size:10px;line-height:1.4}.footer{margin-top:18px;color:var(--muted);font-size:12px;text-align:center}.dark{--bg:#1c2420;--surface:#27312c;--ink:#eef4ee;--muted:#a9b5ac;--line:#435047;--strong-line:#718178;--accent:#8bd0af;--accent-soft:#315347;--danger:#f08d83;--shadow:0 18px 45px rgba(0,0,0,.2)}.dark .cell.given{background:#303b35}.dark .cell.related{background:#3c6453}.dark .cell.selected{background:#4f8b70}@media(max-width:760px){.app-shell{padding-top:22px}.game-layout{grid-template-columns:1fr}.side-panel{display:grid;grid-template-columns:1fr 1fr;gap:18px}.control-section+.control-section,.stats-section{border-top:0;margin-top:0;padding-top:0}.stats-section{grid-column:1 / -1;border-top:1px solid var(--line);padding-top:18px}.quick-actions{gap:3px}.quick-action{width:29px;height:29px;flex-basis:29px;font-size:14px}}@media(max-width:460px){.app-shell{width:min(100% - 18px,1080px)}.board-panel{padding:12px 8px}.side-panel{padding:16px;grid-template-columns:1fr}.stats-section{grid-column:auto}}