: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}.mobile-actions{display:none}.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}.topbar-links{display:flex;gap:8px}.icon-button{width:40px;height:40px;display:grid;place-items:center;padding:0;border:1px solid var(--line);background:var(--surface);border-radius:8px;font-size:20px;text-decoration:none}.guide-link{color:var(--accent);font-size:17px;font-weight:800}.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.active{border-color:var(--accent);background:var(--accent-soft);color:var(--accent)}.board{position:relative;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.number-influence{background:#dce5f5}.cell.number-focus{background:#f0cf80;color:#193e34;box-shadow:inset 0 0 0 2px #c08b25;z-index:1}.cell.hint-target{background:#f2dda7;box-shadow:inset 0 0 0 2px #b47d18;z-index:1}.cell.chain-node-cell{background:#e4eef8;box-shadow:inset 0 0 0 2px #3d74a8;z-index:2}.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}.chain-overlay{position:absolute;inset:0;z-index:4;pointer-events:none;overflow:visible}.chain-arrow{stroke:#2f6f5e;stroke-width:.46;stroke-linecap:round;marker-end:url(#chain-arrow-head);filter:drop-shadow(0 1px 1px rgba(255,255,255,.75));animation:chain-draw 2.8s ease-in-out infinite}.chain-arrow.weak{stroke:#9b5b1f;stroke-dasharray:2 1.4}.chain-overlay marker path{fill:#2f6f5e}.chain-node-marker circle{fill:#fffdf9;stroke:#2f6f5e;stroke-width:.45;filter:drop-shadow(0 1px 1px rgba(0,0,0,.22))}.chain-node-marker text{fill:#1e2420;font-size:2.35px;font-weight:850;text-anchor:middle;pointer-events:none}.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)}.hint-panel{max-width:560px;margin:0 auto 14px;padding:10px 12px;display:flex;gap:10px;align-items:flex-start;border-left:3px solid #b47d18;background:#faf3df;color:#54411f;font-size:13px;line-height:1.55}.hint-panel strong{flex:0 0 auto;color:#805711}.hint-copy{min-width:0;display:grid;gap:8px}.hint-method-link{width:max-content;max-width:100%;color:#805711;font-size:12px;font-weight:800;text-decoration:underline;text-underline-offset:3px;overflow-wrap:anywhere}.chain-steps{display:grid;grid-template-columns:repeat(auto-fit,minmax(122px,1fr));gap:6px}.chain-step{min-width:0;display:grid;grid-template-columns:22px minmax(0,1fr);gap:2px 7px;padding:6px 7px;border:1px solid rgba(84,65,31,.18);border-radius:6px;background:#ffffff6b}.chain-step b{grid-row:span 2;width:22px;height:22px;display:grid;place-items:center;border-radius:50%;background:#2f6f5e;color:#fff;font-size:11px;line-height:1}.chain-step.weak b{background:#9b5b1f}.chain-step span{min-width:0;color:#4c3920;font-size:12px;font-weight:800;overflow-wrap:anywhere}.chain-step small{min-width:0;color:#7b6847;font-size:10px;font-weight:750;overflow-wrap:anywhere}.chain-notation{min-width:0}.chain-notation summary{width:max-content;max-width:100%;color:#805711;cursor:pointer;font-size:12px;font-weight:800}.chain-notation code{display:block;margin-top:5px;padding:6px 7px;border-radius:5px;background:#ffffff73;color:#54411f;font-size:11px;white-space:normal;overflow-wrap:anywhere}.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{position:relative;touch-action:manipulation;user-select:none;-webkit-user-select:none;-webkit-touch-callout:none;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 .number-count{position:absolute;top:4px;right:6px;color:var(--muted);font-size:9px;font-weight:600;line-height:1}.number-pad .erase{grid-column:span 2;color:var(--muted);font-size:13px;font-weight:600}@media(hover:hover){.quick-action:hover{border-color:var(--accent);background:var(--accent-soft);color:var(--accent)}}.side-panel{padding:22px}.control-section+.control-section,.stats-section,.hint-history-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}.hint-history-section details{min-width:0}.hint-history-section>details>summary{min-height:30px;display:flex;align-items:center;justify-content:space-between;gap:10px;cursor:pointer;list-style:none}.hint-history-section summary::-webkit-details-marker{display:none}.hint-history-section>details>summary strong{color:var(--accent);font-variant-numeric:tabular-nums;font-size:13px}.hint-history-list{max-height:280px;overflow:auto;display:grid;gap:8px;margin-top:12px;padding-right:3px}.hint-history-item{min-width:0;padding:9px;border:1px solid var(--line);border-radius:7px;background:#ffffff47}.hint-history-head{display:flex;justify-content:space-between;gap:8px;color:var(--ink);font-size:12px}.hint-history-head strong,.hint-history-head span{min-width:0;overflow-wrap:anywhere}.hint-history-head span{flex:0 0 auto;color:var(--muted);font-variant-numeric:tabular-nums}.hint-history-item p{margin:6px 0 0;color:var(--muted);font-size:11px;line-height:1.55;overflow-wrap:anywhere}.hint-history-item small{display:block;margin-top:5px;color:var(--muted);font-size:10px;line-height:1.45;overflow-wrap:anywhere}.hint-history-item details{margin-top:6px}.hint-history-item details summary{width:max-content;max-width:100%;color:var(--accent);cursor:pointer;font-size:11px;font-weight:800;list-style:none}.empty-history{margin:10px 0 0;color:var(--muted);font-size:12px}.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}.dark .cell.number-influence{background:#3b4c68}.dark .cell.number-focus{background:#9b7427;color:#fff}.dark .cell.hint-target{background:#73591e;color:#fff}.dark .cell.chain-node-cell{background:#2d4d68}.dark .hint-panel{background:#43391f;color:#f0dfb5}.dark .hint-panel strong{color:#f4c761}.dark .chain-node-marker circle{fill:#27312c}.dark .chain-node-marker text{fill:#eef4ee}.dark .chain-step{background:#ffffff12;border-color:#f4c7612e}.dark .chain-step span{color:#f0dfb5}.dark .chain-step small{color:#d0bd8a}.dark .chain-notation code{background:#ffffff14;color:#f0dfb5}@keyframes chain-draw{0%,to{opacity:.5;stroke-width:.42}45%,70%{opacity:.9;stroke-width:.62}}@media(max-width:760px){.app-shell{padding-top:22px}.topbar{display:grid;grid-template-columns:auto minmax(0,1fr) auto;gap:8px;align-items:center}.mobile-actions{display:flex;justify-content:center;gap:4px;min-width:0}.mobile-actions .quick-action{width:32px;height:32px;flex-basis:32px;font-size:15px}.board-head{grid-template-columns:auto minmax(0,1fr) auto}.board-head .mobile-primary{display:none}.board-head .quick-actions{gap:5px}.game-layout{grid-template-columns:1fr}.side-panel{display:grid;grid-template-columns:1fr 1fr;gap:18px}.control-section+.control-section,.stats-section,.hint-history-section{border-top:0;margin-top:0;padding-top:0}.stats-section,.hint-history-section{grid-column:1 / -1;border-top:1px solid var(--line);padding-top:18px}}@media(max-width:460px){.app-shell{width:min(100% - 18px,1080px)}.topbar{gap:4px}.topbar h1{font-size:22px}.topbar .eyebrow{display:none}.mobile-actions{gap:3px}.mobile-actions .quick-action{width:29px;height:30px;flex-basis:29px;font-size:14px}.topbar-links{gap:4px}.icon-button{width:32px;height:32px;font-size:17px}.board-panel{padding:12px 8px}.board-head{gap:6px}.difficulty-display .label{display:none}.board-head .quick-action{width:30px;height:30px;flex-basis:30px;font-size:14px}.timer{font-size:18px}.side-panel{padding:16px;grid-template-columns:1fr}.stats-section{grid-column:auto}}@media(prefers-reduced-motion:reduce){.chain-arrow{animation:none;opacity:1}}