:root{color-scheme:light;--background:#f7f3ea;--surface:#fffdf8;--surface-strong:#f0e7d8;--foreground:#1f1a14;--muted:#6a6258;--border:#d2c5af;--accent:#996b2e}*{box-sizing:border-box}body,html{margin:0;min-height:100%;padding:0}body{background:radial-gradient(circle at top,rgba(153,107,46,.12),transparent 35%),linear-gradient(180deg,#fbf7ef 0,var(--background) 100%);color:var(--foreground);font-family:Georgia,Times New Roman,serif}a{color:inherit;text-decoration:none}.site-header{border-bottom:1px solid rgba(31,26,20,.08);background:rgba(255,253,248,.86);-webkit-backdrop-filter:blur(8px);backdrop-filter:blur(8px)}.site-header-inner{display:flex;justify-content:space-between;align-items:center;gap:1rem;margin:0 auto;max-width:72rem;padding:1rem 1.25rem}.site-brand{font-size:1rem;font-weight:700;letter-spacing:.04em;text-transform:uppercase}.site-nav{display:flex;gap:1rem}.site-nav-link{color:var(--muted);font-size:.95rem}.breadcrumbs{margin-bottom:1.25rem}.breadcrumbs ol{display:flex;flex-wrap:wrap;gap:.5rem;margin:0;padding:0;list-style:none;color:var(--muted);font-size:.92rem}.breadcrumbs li:not(:last-child):after{content:"/";margin-left:.5rem}.content-hero{margin-top:2rem;border:1px solid var(--border);border-radius:1.25rem;background:rgba(255,253,248,.78);padding:1.5rem}.content-hero h1,.content-hero h2{margin:0;font-size:clamp(1.75rem,3vw,2.5rem);line-height:1.1}.content-hero p{max-width:50rem;color:var(--muted);line-height:1.6}.difficulty-strip{display:flex;flex-wrap:wrap;gap:.75rem;margin-top:1.5rem}.difficulty-pill{border:1px solid var(--border);border-radius:999px;background:rgba(240,231,216,.6);padding:.55rem .9rem;color:var(--foreground);font-size:.92rem;font-weight:700}.puzzle-card-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(16rem,1fr));grid-gap:1rem;gap:1rem;margin-top:1.5rem}.puzzle-card{display:flex;flex-direction:column;gap:.75rem;border:1px solid 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p{max-width:48rem;color:var(--muted);font-size:1.05rem;line-height:1.6}.status-row{display:flex;flex-wrap:wrap;gap:.75rem;align-items:center;margin-top:2rem}.status-badge{border-radius:999px;padding:.45rem .85rem;font-size:.85rem;font-weight:700;text-transform:uppercase;letter-spacing:.05em}.status-idle,.status-in-progress{background:var(--surface-strong);color:var(--foreground)}.status-invalid{background:#f5d9d6;color:#7e1c10}.status-completed{background:#d8ead7;color:#245a22}.status-caption{color:var(--muted);font-size:.95rem}.play-area{display:grid;grid-template-columns:minmax(0,1.6fr) minmax(16rem,.8fr);grid-gap:1.5rem;gap:1.5rem;align-items:start;margin-top:1.5rem}.board-frame{width:100%;max-width:min(100%,42rem);overflow:hidden;border:2px solid var(--foreground);border-radius:1rem;background:var(--surface)}.sudoku-grid{display:grid;grid-template-columns:repeat(9,minmax(0,1fr))}.sudoku-cell{aspect-ratio:1;display:flex;align-items:center;justify-content:center;margin:0;padding:0;background:transparent;border-top:0;border-left:0;border-right:1px solid var(--border);border-bottom:1px solid var(--border);color:var(--foreground);font:inherit;font-size:clamp(1rem,2vw,1.5rem);font-weight:700;cursor:pointer;touch-action:manipulation;-webkit-tap-highlight-color:transparent;transition:background-color .12s ease,color .12s ease,box-shadow .12s ease}.sudoku-cell:nth-child(9n){border-right:none}.sudoku-cell:nth-child(n+73){border-bottom:none}.sudoku-cell:nth-child(3n):not(:nth-child(9n)){border-right:2px solid var(--foreground)}.sudoku-cell:nth-child(n+19):nth-child(-n+27),.sudoku-cell:nth-child(n+46):nth-child(-n+54){border-bottom:2px solid var(--foreground)}.sudoku-cell.is-given{background:var(--surface-strong);color:var(--foreground)}.sudoku-cell.is-editable{color:var(--accent)}.sudoku-cell.is-highlighted-region{background:#f6efe2}.sudoku-cell.is-highlighted-value{background:#efe3c8}.sudoku-cell.is-selected{background:#f4e1bf;box-shadow:inset 0 0 0 3px var(--accent)}.sudoku-cell.is-conflicting{background:#fbe1dd;color:#8f2619}.sudoku-cell:focus-visible{outline:3px solid var(--accent);outline-offset:-3px}.control-panel{width:100%;border:1px solid var(--border);border-radius:1rem;background:rgba(240,231,216,.5);padding:1rem}.keypad{display:grid;grid-template-columns:repeat(3,minmax(0,1fr));grid-gap:.75rem;gap:.75rem}.keypad-button{min-height:3rem;border:1px solid var(--border);border-radius:.8rem;background:var(--surface);color:var(--foreground);font:inherit;font-size:1rem;font-weight:700;cursor:pointer;touch-action:manipulation}.keypad-button:disabled{opacity:.5;cursor:not-allowed}.keypad-clear{grid-column:1/-1}.legend{margin:1rem 0 0;padding-left:1.1rem;color:var(--muted);line-height:1.6}.sr-only{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip:rect(0,0,0,0);white-space:nowrap;border:0}@media (max-width:640px){.site-header-inner{padding:.875rem}.site-nav{gap:.75rem}.page-shell{padding:1rem .875rem 2rem}.board-shell{padding:1rem}.content-hero{margin-top:1.25rem;padding:1rem}.status-row{gap:.5rem;margin-top:1.25rem}.status-caption{width:100%;font-size:.9rem}.keypad{gap:.5rem}.keypad-button{min-height:3.25rem}}@media (max-width:900px){.play-area{grid-template-columns:1fr}.board-frame{margin-inline:auto}}