:root{--color-surface:#f7f5f0;--color-surface-2:#edecea;--color-surface-3:#e3e1da;--color-surface-invert:#1c1b18;--color-text-primary:#1c1b18;--color-text-secondary:#6b6960;--color-text-tertiary:#9b9890;--color-text-on-invert:#f7f5f0;--color-text-on-accent:#fff;--color-accent:#2a6b6b;--color-accent-hover:#215555;--color-accent-light:#e4efef;--color-border:#dddbd4;--color-border-strong:#aeaca5;--font-ui:"Outfit", "Avenir Next", "Segoe UI", system-ui, sans-serif;--font-display:"Cormorant Garamond", "Iowan Old Style", Georgia, serif;--font-mono:"Space Mono", ui-monospace, Consolas, 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var(--focus-ring);outline-offset:3px}.footer-store__icon{flex-shrink:0}.footer-lang__switcher{flex-direction:column;gap:.25rem;display:inline-flex}.footer-lang__button{appearance:none;color:var(--color-text-tertiary);cursor:pointer;font-family:var(--font-ui);letter-spacing:.02em;text-align:left;transition:color var(--transition-base);background:0 0;border:none;padding:.25rem 0;font-size:.85rem;font-weight:500;line-height:1;text-decoration:none}.footer-lang__button:hover,.footer-lang__button:focus-visible{color:var(--color-accent)}.footer-lang__button:focus-visible{outline:2px solid var(--focus-ring);outline-offset:2px;border-radius:var(--radius-sm)}.footer-lang__button--active{color:var(--color-text-primary);font-weight:700}.site-footer__bottom{border-top:1px solid var(--color-border);flex-wrap:wrap;justify-content:space-between;align-items:center;gap:1rem;max-width:1160px;margin:1.5rem auto 0;padding-top:1rem;display:flex}.footer-legal{font-family:var(--font-mono);color:var(--color-text-tertiary);letter-spacing:.08em;font-size:.6875rem}@media (width<=768px){.site-footer{padding-left:1rem;padding-right:1rem}.site-footer__inner{grid-template-columns:1fr 1fr;row-gap:1.75rem}.footer-brand{grid-column:1/-1}}@media (width<=480px){.site-footer__inner{grid-template-columns:1fr}.footer-brand{grid-column:auto}}.sudoku-board-wrapper{gap:12px;display:grid;container-type:inline-size}.sudoku-board{grid-template-columns:repeat(var(--sudoku-size), minmax(0, 1fr));grid-template-rows:repeat(var(--sudoku-size), minmax(0, 1fr));aspect-ratio:1;border:2px solid var(--text-h);background:color-mix(in srgb, var(--surface,var(--bg)) 80%, var(--text-h) 20%);box-sizing:border-box;width:100%;display:grid}.sudoku-cell{border-right:1px solid color-mix(in srgb, var(--text-h) 40%, transparent);border-bottom:1px solid color-mix(in srgb, var(--text-h) 40%, 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0;font-size:clamp(.95rem,1.6vw,1.2rem);line-height:1}.sudoku-symbol-button:hover{background:color-mix(in srgb, var(--surface,var(--bg)) 86%, var(--text-h) 14%)}.sudoku-symbol-button:focus-visible{outline:2px solid color-mix(in srgb, var(--sudoku-accent) 85%, var(--text-h) 15%);outline-offset:2px}.sudoku-symbol-button--selected{background:var(--sudoku-accent);border-color:var(--sudoku-accent);color:var(--sudoku-accent-contrast,#fff)}.sudoku-symbol-button--selected:hover{background:color-mix(in srgb, var(--sudoku-accent) 82%, black);border-color:color-mix(in srgb, var(--sudoku-accent) 82%, black);color:var(--sudoku-accent-contrast,#fff)}@media (width<=1024px){.sudoku-cell__value{font-size:clamp(1.15rem,3vw,2.05rem)}.sudoku-symbol-button{font-size:clamp(1rem,2.1vw,1.25rem)}}@media (width<=700px){.sudoku-cell__value{font-size:clamp(1.05rem,4.2vw,1.9rem)}}@media 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.vl-section-label{padding-top:0;padding-bottom:1rem}.learn-tier{flex-direction:column;gap:.75rem;display:flex}.learn-tier+.learn-tier{margin-top:2rem}.learn-tier__label{font-family:var(--font-ui);letter-spacing:-.02em;color:var(--color-text-primary);margin:0;font-size:1.0625rem;font-weight:700;line-height:1.2}.article-layout{align-items:flex-start;gap:2rem;max-width:960px;margin:0 auto;padding-top:clamp(2rem,4vw,3.5rem);display:flex}.article-sidebar{flex-shrink:0;padding-top:clamp(24px,5vw,56px);display:none}@media (width>=1024px){.article-sidebar{display:block}}.article-page{box-sizing:border-box;flex:1;width:100%;min-width:0}.article-ad-below{justify-content:center;margin-top:3rem;display:flex}@media (width>=1024px){.article-ad-below{display:none}}.article-breadcrumb{margin-bottom:2.25rem}.article-breadcrumb a{font-family:var(--font-ui);color:var(--color-text-secondary);transition:color var(--transition-base);font-size:.875rem;font-weight:500;text-decoration:none}.article-breadcrumb 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p{font-family:var(--font-ui);color:var(--color-text-primary);margin:0;font-size:.9375rem;line-height:1.7}.article-related,.article-sources{border-top:1px solid var(--color-border);flex-direction:column;gap:1rem;margin-top:3rem;padding-top:2rem;display:flex}.article-sources{margin-top:2rem}.article-related__title,.article-sources__title{font-family:var(--font-mono);letter-spacing:.18em;text-transform:uppercase;color:var(--color-text-tertiary);margin:0;font-size:.625rem;font-weight:700}.article-related__list,.article-sources__list{flex-direction:column;gap:.625rem;margin:0;padding:0;list-style:none;display:flex}.article-related__link,.article-sources__link{font-family:var(--font-ui);color:var(--color-accent);transition:color 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p{max-width:70ch}.sudoku-example__boards{grid-template-columns:repeat(auto-fit,minmax(280px,1fr));gap:24px;display:grid}.sudoku-example article{border:1px solid var(--border);border-radius:var(--radius-sm);background:color-mix(in srgb, var(--bg) 92%, var(--text-h) 8%);flex-direction:column;gap:12px;padding:16px;display:flex}.sudoku-example h2{margin:0}.sudoku-example__dynamic{flex-direction:column;gap:12px;display:flex}.sudoku-dynamic-grid{grid-template-columns:repeat(2,minmax(0,1fr));align-items:start;gap:16px;display:grid}.sudoku-dynamic-grid>*{min-width:0}.sudoku-dynamic-form{flex-direction:column;gap:8px;min-width:0;display:flex}.sudoku-dynamic-form label{color:var(--text-h);font-weight:600}.sudoku-dynamic-form input:not([type=checkbox]),.sudoku-dynamic-form textarea{border-radius:var(--radius-sm);border:1px solid var(--border);background:var(--bg);width:100%;color:var(--text-h);box-sizing:border-box;font:inherit;padding:10px 12px}.sudoku-dynamic-form 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var(--border);border-radius:var(--radius-sm);background:color-mix(in srgb, var(--bg) 94%, var(--text-h) 6%);margin-top:4px;padding:10px}.sudoku-color-legend__title{color:var(--text-h);margin-bottom:8px;font-weight:600;display:block}.sudoku-color-legend ul{grid-template-columns:repeat(auto-fit,minmax(150px,1fr));gap:6px 10px;margin:0;padding:0;list-style:none;display:grid}.sudoku-color-legend li{align-items:center;gap:8px;display:flex}.sudoku-color-legend__chip{border-radius:var(--radius-pill);border:1px solid color-mix(in srgb, var(--legend-color) 70%, var(--text-h) 30%);background:var(--legend-color);width:12px;height:12px;display:inline-block}@media (width<=1024px){.sudoku-dynamic-grid{grid-template-columns:1fr}}.app-shell{box-sizing:border-box;flex-direction:column;width:100%;min-height:100svh;display:flex}.skip-to-main{z-index:calc(var(--z-header) + 10);background:var(--accent);color:var(--surface);border-radius:0 0 var(--radius-sm) var(--radius-sm);font:600 .9rem/1 var(--sans);transition:top var(--transition-fast);padding:12px 20px;text-decoration:none;position:absolute;top:-100%;left:50%;transform:translate(-50%)}.skip-to-main:focus{outline:3px solid var(--focus-ring);outline-offset:2px;top:0}.site-header{z-index:var(--z-header);background:color-mix(in srgb, var(--color-surface) 88%, transparent);-webkit-backdrop-filter:blur(16px);border-bottom:1px solid var(--color-border);padding:0 2rem;position:sticky;top:0}.site-header__inner{align-items:center;gap:8px;max-width:1160px;height:64px;margin:0 auto;display:flex}@media (width<=640px){.site-header{padding:0 1rem}}.brand-link{color:var(--color-text-primary);flex-shrink:0;align-items:center;gap:9px;text-decoration:none;display:flex}.brand-link:hover .brand-link__text,.brand-link:focus-visible 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10px;font-size:.875rem;font-weight:500;line-height:1;text-decoration:none}.site-nav__link:hover,.site-nav__link:focus-visible{color:var(--color-text-primary)}.site-nav__link:focus-visible{outline:3px solid var(--focus-ring);outline-offset:2px;border-radius:var(--radius-sm)}.site-nav__link--active{color:var(--color-accent)}.header-cta{font-family:var(--font-ui);letter-spacing:.01em;border-radius:var(--radius-md);background:var(--color-text-primary);color:var(--color-text-on-invert);cursor:pointer;transition:background-color var(--transition-base);border:none;flex-shrink:0;justify-content:center;align-items:center;gap:.5rem;margin-left:auto;padding:.625rem 1.25rem;font-size:.875rem;font-weight:700;line-height:1;text-decoration:none;display:inline-flex}.header-cta:hover{background:var(--color-accent)}.header-cta:focus-visible{outline:3px solid var(--focus-ring);outline-offset:3px}.header-cta__label{display:inline}.header-cta__icon{display:none}.language-switcher{border:1px solid var(--color-border);border-radius:var(--radius-md);background:var(--color-surface-2);flex-shrink:0;align-items:center;gap:2px;padding:3px;display:inline-flex}.language-switcher__button{appearance:none;border-radius:var(--radius-sm);color:var(--color-text-tertiary);cursor:pointer;font-family:var(--font-mono);letter-spacing:.08em;transition:background-color var(--transition-base), color var(--transition-base);background:0 0;border:none;justify-content:center;align-items:center;padding:6px 8px;font-size:.6875rem;font-weight:700;line-height:1;text-decoration:none;display:inline-flex}.language-switcher__button:hover,.language-switcher__button:focus-visible{color:var(--color-text-primary)}.language-switcher__button:focus-visible{outline:3px solid var(--focus-ring);outline-offset:2px}.language-switcher__button--active{background:var(--color-text-primary);color:var(--color-text-on-invert)}.language-switcher__button--active:hover,.language-switcher__button--active:focus-visible{color:var(--color-text-on-invert)}.app-layout{flex:1;padding:0 0 5rem}.app-layout__inner{width:100%}.ad-slot{border:1px dashed var(--border-strong);border-radius:var(--radius-sm);color:var(--muted);text-transform:uppercase;letter-spacing:.08em;background:color-mix(in srgb, var(--surface) 84%, var(--surface-strong) 16%);box-sizing:border-box;place-items:center;font-size:.75rem;display:grid}.ad-slot--300x250{width:300px;max-width:100%;height:250px}.ad-slot--160x600{width:160px;height:600px}@media (width<=768px){.site-header__inner{gap:6px}.site-nav{margin-left:12px}.header-cta__label{display:none}.header-cta__icon{display:inline}}@media (width<=640px){.site-nav,.language-switcher{display:none}}