:root{color-scheme:light;--bg:#eef3ef;--bg-soft:#f7f1e8;--surface:#fffaf2;--surface-strong:#fff5e2;--ink:#1f2d2b;--muted:#687874;--line:#d6ded7;--line-strong:#8fa59e;--accent:#2a9d8f;--accent-dark:#237f76;--accent-soft:#d9f0ea;--warn:#c76f45;--shadow:0 24px 60px #1e3a351f;font-family:Inter,ui-sans-serif,system-ui,-apple-system,BlinkMacSystemFont,Segoe UI,sans-serif}*{box-sizing:border-box}html{color:var(--ink);background:radial-gradient(circle at 0 0,#2a9d8f1f,#0000 30rem),linear-gradient(135deg,#eef3ef 0%,#f7f1e8 58%,#e6efee 100%)}body{min-height:100vh;margin:0}a{color:var(--accent-dark)}button,input,select{font:inherit}button{cursor:pointer}.page-shell{width:min(1180px,100% - 32px);margin:0 auto}.site-header{justify-content:space-between;align-items:center;gap:24px;padding:14px 0;display:flex}.brand{color:var(--ink);align-items:center;gap:12px;font-weight:800;text-decoration:none;display:inline-flex}.brand-mark{width:38px;height:38px;color:var(--surface);background:#264653;border-radius:10px;place-items:center;font-size:20px;display:grid}.nav{flex-wrap:wrap;gap:14px;display:flex}.nav-menu{position:relative}.nav-menu summary{display:none}.nav a{color:var(--muted);font-size:.95rem;font-weight:650;text-decoration:none}.nav a:hover{color:var(--accent-dark)}.hero{grid-template-columns:minmax(0,1fr);gap:12px;padding:4px 0 16px;display:grid}.hero-copy{max-width:820px}.eyebrow{color:var(--accent-dark);letter-spacing:.08em;text-transform:uppercase;font-size:.82rem;font-weight:800}h1,h2,h3{margin:0;line-height:1.08}h1{max-width:860px;margin-top:10px;font-size:clamp(2rem,6vw,3.8rem)}h2{font-size:clamp(1.45rem,3vw,2.15rem)}h3{font-size:1.25rem}p{color:var(--muted);line-height:1.7}.lede{max-width:720px;margin:10px 0 0;font-size:1rem}.content-band{padding:22px 0}.content-grid{grid-template-columns:repeat(3,minmax(0,1fr));gap:14px;margin-top:12px;display:grid}.info-card{border:1px solid var(--line);background:#fffaf2b3;border-radius:8px;padding:16px}.faq-list{gap:10px;margin-top:12px;display:grid}.faq-list details{border:1px solid var(--line);background:#fffaf2b8;border-radius:8px;padding:14px 16px}.faq-list summary{color:var(--ink);cursor:pointer;font-weight:800}.site-footer{color:var(--muted);padding:20px 0}.sudoku-app{background:linear-gradient(180deg, #fffaf2f0, #f7f1e8e6), var(--surface);border:1px solid #8fa59e8c;border-radius:8px;width:min(100%,820px);max-width:100%;margin:0 auto;padding:clamp(14px,2vw,20px);box-shadow:0 14px 34px #1e3a351a}.sudoku-toolbar,.sudoku-status{flex-wrap:wrap;align-items:center;gap:14px;display:flex}.sudoku-toolbar{justify-content:flex-start}.sudoku-toolbar label{color:var(--muted);text-transform:uppercase;gap:5px;font-size:.82rem;font-weight:800;display:grid}.sudoku-toolbar select,.sudoku-toolbar button,.control-grid button,.number-pad button{border:1px solid var(--line);color:var(--ink);background:#ffffffa6;border-radius:8px;font-weight:800}.sudoku-toolbar select{min-width:150px;padding:9px 11px}.sudoku-toolbar button,.control-grid button{padding:10px 12px}.primary-action{border-color:#0000;background:var(--accent)!important;color:#fff!important}.sudoku-status{color:var(--muted);justify-content:flex-start;margin:10px 0 12px;font-size:.9rem;font-weight:750}.sudoku-status span{padding:0}.sudoku-stage{grid-template-columns:minmax(320px,440px) minmax(260px,300px);justify-content:center;align-items:start;gap:clamp(18px,3vw,28px);display:grid}.sudoku-board{grid-template-columns:repeat(var(--sudoku-size), minmax(0, 1fr));aspect-ratio:1;background:#264653;border:3px solid #264653;border-radius:8px;width:min(100%,440px);display:grid;overflow:hidden}.sudoku-app[data-current-mode=mini] .sudoku-board{width:min(100%,320px)}.sudoku-app[data-current-mode=medium] .sudoku-board{width:min(100%,380px)}.sudoku-app[data-current-mode=classic] .sudoku-board{width:min(100%,440px)}.sudoku-cell{min-width:0;min-height:0;color:var(--ink);background:#fffbf3;border:1px solid #2646532e;place-items:center;font-size:clamp(1rem,4vw,2.1rem);font-weight:800;display:grid;position:relative}.sudoku-cell.is-box-edge-x{border-right:3px solid #264653}.sudoku-cell.is-box-edge-y{border-bottom:3px solid #264653}.sudoku-cell:nth-child(odd){background:#fffaf0}.sudoku-cell.is-related{background:#edf6f2}.sudoku-cell.is-selected{outline:2px solid var(--accent);outline-offset:-2px;z-index:1}.sudoku-cell.is-fixed{color:#172d33;background:#d8e3df;font-weight:900;box-shadow:inset 0 0 0 999px #26465309}.sudoku-cell.is-error{color:#9b3f2d;background:#ffe5dc}.sudoku-cell.is-complete{background:#dff3e9}.sudoku-cell.is-flash-complete{animation:.85s ease-out unit-complete}.sudoku-cell.is-flash-board{animation:.9s ease-out board-complete}.sudoku-cell.is-flash-error{animation:.7s ease-out cell-error}.cell-notes{max-width:80%;color:var(--muted);text-align:center;white-space:normal;font-size:clamp(.5rem,1.4vw,.82rem);font-weight:700;line-height:1.2;display:block}.sudoku-panel{gap:14px;width:100%;display:grid}.number-pad{grid-template-columns:repeat(3,minmax(0,1fr));gap:10px;display:grid}.number-pad button{aspect-ratio:1;background:var(--surface-strong);color:var(--accent-dark);font-size:1.25rem}.control-grid{grid-template-columns:repeat(2,minmax(0,1fr));gap:10px;display:grid}.control-grid button{justify-content:center;align-items:center;gap:7px;min-height:46px;display:inline-flex}.action-icon{flex:none;justify-content:center;align-items:center;display:inline-flex}.action-icon svg{display:block}.action-icon-play,.action-label-play,[data-action=pause][data-paused=true] .action-icon-pause,[data-action=pause][data-paused=true] .action-label-pause{display:none}[data-action=pause][data-paused=true] .action-icon-play,[data-action=pause][data-paused=true] .action-label-play{display:inline-flex}.control-grid button.is-active{border-color:var(--accent);background:var(--accent-soft);color:var(--accent-dark)}@keyframes unit-complete{0%{background:#fffbf3}35%{background:#cfeee4}to{background:inherit}}@keyframes board-complete{0%{background:#fffbf3;transform:scale(1)}35%{background:#cfeee4;transform:scale(1.015)}to{background:inherit;transform:scale(1)}}@keyframes cell-error{0%,to{background:#ffe5dc}45%{background:#f6b7a5}}@media (width<=780px){.site-header{flex-direction:row;align-items:center;gap:12px}.nav-menu{margin-left:auto}.nav-menu summary{border:1px solid var(--line);cursor:pointer;background:#fffaf2e0;border-radius:8px;place-content:center;gap:5px;width:42px;height:42px;list-style:none;display:grid}.nav-menu summary::-webkit-details-marker{display:none}.nav-menu summary span{background:var(--ink);border-radius:999px;width:18px;height:2px;display:block}.nav{z-index:10;border:1px solid var(--line);background:var(--surface);min-width:180px;box-shadow:var(--shadow);border-radius:8px;flex-direction:column;gap:0;padding:8px;display:none;position:absolute;top:calc(100% + 8px);right:0}.nav-menu[open] .nav{display:flex}.nav a{padding:10px 12px}.hero{padding-bottom:16px}.content-band{padding:20px 0}.content-grid{grid-template-columns:1fr}.sudoku-stage{grid-template-columns:1fr;justify-content:stretch;gap:12px}.sudoku-panel{width:100%}.sudoku-board{width:min(100%,100vw - 64px)!important}.number-pad{grid-template-columns:repeat(var(--sudoku-size), minmax(0, 1fr))}.control-grid{grid-template-columns:repeat(7,minmax(42px,1fr))}.control-grid button{justify-content:center;min-height:44px;padding:0}.action-label{display:none!important}.control-grid .action-icon{display:inline-flex}.control-grid .action-icon svg{width:19px;height:19px}}