:root{--font-serif:"Literata", "Iowan Old Style", Georgia, serif;--font-sans:"Libre Franklin", "Segoe UI", sans-serif;--radius-sm:3px;--radius-md:6px;--radius-lg:10px;font-family:var(--font-sans);-webkit-font-smoothing:antialiased;-moz-osx-font-smoothing:grayscale;--color-desk:oklch(90% .023 72);--color-paper:oklch(97.5% .012 85);--color-paper-inset:oklch(93.5% .018 78);--color-ink:oklch(21% .02 50);--color-ink-soft:oklch(40% .02 50);--color-ink-faint:oklch(55% .017 55);--color-rule:oklch(80% .018 65);--color-rule-strong:var(--color-ink);--color-pen:oklch(47% .13 78);--color-pen-soft:oklch(90% .05 82);--color-pencil:oklch(46% .028 250);--color-highlight:oklch(89% .07 92);--color-highlight-border:oklch(63% .1 75);--color-success:oklch(42% .09 150);--color-success-bg:oklch(93% .05 150);--color-success-border:oklch(68% .1 150);--color-error:oklch(46% .15 27);--color-error-bg:oklch(93% .04 30);--color-error-border:oklch(67% .12 30);color:var(--color-ink);background:var(--color-desk);font-weight:400;line-height:1.5}:root[data-theme=dark]{--color-desk:oklch(11.5% .005 50);--color-paper:oklch(17.5% .007 50);--color-paper-inset:oklch(23% .009 50);--color-ink:oklch(93% .008 75);--color-ink-soft:oklch(76% .009 70);--color-ink-faint:oklch(55% .009 65);--color-rule:oklch(31% .011 55);--color-rule-strong:var(--color-ink);--color-pen:oklch(76% .1 195);--color-pen-soft:oklch(26% .05 195);--color-pencil:oklch(74% .045 245);--color-highlight:oklch(30% .055 195);--color-highlight-border:oklch(60% .1 195);--color-success:oklch(76% .13 150);--color-success-bg:oklch(22% .045 150);--color-success-border:oklch(46% .1 150);--color-error:oklch(70% .17 27);--color-error-bg:oklch(24% .055 30);--color-error-border:oklch(52% .14 30)}*{box-sizing:border-box}::selection{background:var(--color-highlight)}body{background:radial-gradient(circle at 12% 8%, oklch(100% 0 0/.4) 0%, transparent 42%), radial-gradient(circle at 88% 92%, oklch(0% 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var(--color-rule-strong)}.cell-notes{grid-template-rows:repeat(3,1fr);grid-template-columns:repeat(3,1fr);place-items:center;padding:.15rem;display:grid;position:absolute;inset:0}.note-value{font-family:var(--font-sans);color:var(--color-pencil);font-size:.56rem;font-weight:600;line-height:1}.panel{background:var(--color-paper);border:1px solid var(--color-rule);border-radius:var(--radius-lg);grid-area:panel;align-content:start;gap:1.1rem;padding:1.1rem;display:grid;box-shadow:0 1px 3px oklch(0% 0 0/.08),0 1px 2px oklch(0% 0 0/.05)}.panel h2{border-bottom:1px solid var(--color-rule);font-family:var(--font-sans);letter-spacing:.09em;text-transform:uppercase;color:var(--color-ink-faint);margin:0;padding-bottom:.5rem;font-size:.78rem;font-weight:700}.difficulty-control{gap:.5rem;display:grid}.difficulty-control label{font-family:var(--font-sans);letter-spacing:.03em;color:var(--color-ink-soft);font-size:.8rem;font-weight:600}.difficulty-row{grid-template-columns:1fr 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