:root{--c-bg: #f0f4f8;--c-surface: #ffffff;--c-border: #cbd5e1;--c-text: #0f172a;--c-text-muted: #64748b;--c-accent: #2563eb;--c-accent-hover: #1d4ed8;--c-accent-soft: #dbeafe;--card-shadow: 0 12px 40px -10px rgba(15,23,42,.18), 0 3px 10px -3px rgba(15,23,42,.08)}@media(prefers-color-scheme:dark){:root:not(.light){--c-bg: #0d1117;--c-surface: #161b22;--c-border: #263040;--c-text: #e2e8f0;--c-text-muted: #8b97a8;--c-accent: #3b82f6;--c-accent-hover: #60a5fa;--c-accent-soft: #172554;--card-shadow: 0 12px 44px -8px rgba(0,0,0,.55), 0 3px 12px -3px rgba(0,0,0,.4)}}:root.dark{--c-bg: #0d1117;--c-surface: #161b22;--c-border: #263040;--c-text: #e2e8f0;--c-text-muted: #8b97a8;--c-accent: #3b82f6;--c-accent-hover: #60a5fa;--c-accent-soft: #172554;--card-shadow: 0 12px 44px -8px rgba(0,0,0,.55), 0 3px 12px -3px rgba(0,0,0,.4)}*{box-sizing:border-box}html{-webkit-text-size-adjust:100%}body{margin:0;background:var(--c-bg);color:var(--c-text);font-family:system-ui,-apple-system,Segoe UI,sans-serif;line-height:1.65;font-size:1.0625rem}a{color:var(--c-accent);text-decoration:none}a:hover{text-decoration:underline}.pk-nav{position:sticky;top:0;z-index:10;display:flex;align-items:center;justify-content:space-between;gap:12px;padding:12px clamp(16px,5vw,32px);background:color-mix(in srgb,var(--c-bg) 86%,transparent);backdrop-filter:blur(8px);border-bottom:1px solid var(--c-border)}.pk-brand{font-size:1.2rem;font-weight:800;letter-spacing:-.03em;color:var(--c-text)}.pk-brand:hover{text-decoration:none}.pk-brand span{color:var(--c-accent)}.pk-play{padding:8px 18px;border-radius:999px;font-size:.9rem;font-weight:600;background:var(--c-accent);color:#fff}.pk-play:hover{background:var(--c-accent-hover);text-decoration:none}.pk-nav-actions{display:flex;align-items:center;gap:10px}.pk-theme-toggle{display:inline-flex;align-items:center;justify-content:center;width:38px;height:38px;padding:0;border:1px solid var(--c-border);border-radius:999px;background:var(--c-surface);cursor:pointer;font-size:1rem;line-height:1}.pk-theme-toggle:hover{border-color:var(--c-accent)}.pk-main{max-width:720px;margin:0 auto;padding:clamp(20px,5vw,44px) clamp(16px,5vw,32px) 8px}.pk-crumb{font-size:.82rem;color:var(--c-text-muted);margin:0 0 14px}.pk-crumb a{color:var(--c-text-muted)}h1{font-size:clamp(1.7rem,5vw,2.4rem);font-weight:800;letter-spacing:-.03em;line-height:1.15;margin:0 0 10px}.pk-lede{font-size:1.15rem;color:var(--c-text-muted);margin:0 0 28px}h2{font-size:1.4rem;font-weight:700;letter-spacing:-.02em;margin:36px 0 12px}h3{font-size:1.1rem;font-weight:700;margin:26px 0 8px}p{margin:0 0 16px}ul,ol{margin:0 0 16px;padding-left:22px}li{margin-bottom:8px}li::marker{color:var(--c-accent)}strong{font-weight:700}.pk-main img{max-width:100%;height:auto}.pk-cta{margin:32px 0;padding:24px;border-radius:16px;background:var(--c-surface);border:1px solid var(--c-border);box-shadow:var(--card-shadow);text-align:center}.pk-cta h2{margin:0 0 6px}.pk-cta p{margin:0 0 16px;color:var(--c-text-muted)}.pk-btn{display:inline-block;padding:12px 28px;border-radius:999px;font-size:1rem;font-weight:600;background:var(--c-accent);color:#fff}.pk-btn:hover{background:var(--c-accent-hover);text-decoration:none}.pk-chips{display:flex;flex-wrap:wrap;gap:8px;margin:0 0 24px;padding:0;list-style:none}.pk-chips li{margin:0}.pk-chips a{display:inline-block;padding:7px 16px;border-radius:999px;font-size:.9rem;font-weight:600;background:var(--c-surface);border:1px solid var(--c-border);color:var(--c-text)}.pk-chips a:hover{border-color:var(--c-accent);color:var(--c-accent);text-decoration:none}.pk-faq h3{margin-bottom:4px}.pk-foot{max-width:720px;margin:40px auto 0;padding:24px clamp(16px,5vw,32px) 36px;border-top:1px solid var(--c-border);text-align:center}.pk-foot-links{display:flex;flex-wrap:wrap;justify-content:center;gap:8px 16px;margin-bottom:14px;font-size:.9rem}.pk-foot-legal{font-size:.8rem;color:var(--c-text-muted);margin:0}.pk-foot-legal strong{color:var(--c-text)}.pk-btn--ghost{background:transparent;color:var(--c-accent);border:1.5px solid var(--c-border)}.pk-btn--ghost:hover{background:var(--c-accent-soft);border-color:var(--c-accent);color:var(--c-accent)}.pk-btn[disabled],.pk-digit[disabled]{opacity:.45;cursor:not-allowed}.pk-sboard{display:grid;grid-template-columns:repeat(var(--n),1fr);width:min(92vw,460px);aspect-ratio:1;margin:20px auto;border:2.5px solid var(--c-text);border-radius:8px;overflow:hidden;background:var(--c-surface);user-select:none}.pk-scell{position:relative;display:flex;align-items:center;justify-content:center;border-right:1px solid var(--c-border);border-bottom:1px solid var(--c-border);font-size:clamp(.9rem,4.2vw,1.5rem);color:var(--c-text);aspect-ratio:1}.pk-scell--br{border-right:2.5px solid var(--c-text)}.pk-scell--bb{border-bottom:2.5px solid var(--c-text)}.pk-scell--hl{background:color-mix(in srgb,var(--c-accent) 22%,transparent)}.pk-scell--place{background:color-mix(in srgb,#16a34a 28%,transparent)}.pk-snum{font-weight:700}.pk-snum--solved{color:var(--c-accent);font-weight:600}.pk-scands{display:grid;grid-template-columns:repeat(3,1fr);width:100%;height:100%;padding:2px;gap:0}.pk-scand{display:flex;align-items:center;justify-content:center;font-size:.5rem;line-height:1;color:var(--c-text-muted);font-style:normal}.pk-scand--off{visibility:hidden}.pk-scand--elim{color:#dc2626;text-decoration:line-through;font-weight:700}.pk-editboard .pk-ecell{cursor:pointer;background:var(--c-surface);padding:0;font-weight:700;color:var(--c-text)}.pk-editboard .pk-ecell{outline:none}.pk-editboard .pk-ecell:focus-visible{outline:2px solid var(--c-accent);outline-offset:-2px}.pk-editboard .pk-ecell--sel{background:color-mix(in srgb,var(--c-accent) 26%,transparent);box-shadow:inset 0 0 0 2px var(--c-accent)}.pk-editboard .pk-ecell--bad{background:color-mix(in srgb,#dc2626 22%,transparent);color:#dc2626}.pk-editboard .pk-scell--hl{background:color-mix(in srgb,var(--c-accent) 22%,transparent)}.pk-editboard .pk-scell--place{background:color-mix(in srgb,#16a34a 28%,transparent)}.pk-solver-tools,.pk-solver-actions,.pk-explain-nav,.pk-daily-controls,.pk-daily-nav{display:flex;flex-wrap:wrap;gap:10px;align-items:center;justify-content:center;margin:16px 0}.pk-seg{display:inline-flex;border:1.5px solid var(--c-border);border-radius:10px;overflow:hidden}.pk-seg-btn{padding:8px 14px;background:transparent;color:var(--c-text);border:none;cursor:pointer;font-weight:600}.pk-seg-btn--on{background:var(--c-accent);color:#fff}.pk-paste{display:flex;flex-direction:column;gap:10px;margin:12px 0}.pk-paste textarea{width:100%;padding:10px;border:1.5px solid var(--c-border);border-radius:10px;background:var(--c-surface);color:var(--c-text);font-family:ui-monospace,monospace;resize:vertical}.pk-digit-pad{display:flex;flex-wrap:wrap;gap:8px;justify-content:center;margin:14px 0}.pk-digit{width:44px;height:48px;border-radius:10px;border:1.5px solid var(--c-border);background:var(--c-surface);color:var(--c-text);font-size:1.25rem;font-weight:700;cursor:pointer}.pk-digit:hover:not([disabled]){border-color:var(--c-accent);color:var(--c-accent)}.pk-digit--erase{font-weight:400}.pk-solver-msg{text-align:center;color:var(--c-text-muted);margin:8px 0}.pk-solver-msg.pk-ok{color:#16a34a}.pk-explain{margin:8px 0 24px}.pk-explain-step{text-align:center;background:var(--c-accent-soft);border-radius:10px;padding:12px 16px}.pk-explain-count{color:var(--c-text-muted);min-width:100px;text-align:center}.pk-solver-copy{margin-top:40px;border-top:1px solid var(--c-border);padding-top:8px}.pk-daily-date{color:var(--c-text-muted);margin:-8px 0 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a:hover{border-color:var(--c-accent);text-decoration:none;box-shadow:var(--card-shadow)}.pk-learn-title{font-weight:700;color:var(--c-text)}.pk-learn-blurb{color:var(--c-text-muted);font-size:.95rem}.pk-learn-more{margin-top:28px;color:var(--c-text-muted)}.pk-example{margin:24px 0;text-align:center}.pk-example figcaption{color:var(--c-text-muted);font-size:.95rem;margin-top:6px}.pk-stat-grid{display:grid;grid-template-columns:repeat(auto-fit,minmax(120px,1fr));gap:14px;margin:20px 0}.pk-stat{background:var(--c-surface);border:1px solid var(--c-border);border-radius:12px;padding:16px;text-align:center}.pk-stat-num{display:block;font-size:2rem;font-weight:800;color:var(--c-accent)}.pk-stat-label{color:var(--c-text-muted);font-size:.9rem}.pk-stat-table{width:100%;border-collapse:collapse;margin:12px 0}.pk-stat-table th,.pk-stat-table td{text-align:left;padding:8px 10px;border-bottom:1px solid var(--c-border)}.pk-heatmap{display:grid;grid-template-columns:repeat(14,1fr);gap:4px;max-width:360px}.pk-heat-cell{aspect-ratio:1;border-radius:3px;background:var(--c-border);display:block}.pk-heat-cell--done{background:#16a34a}.pk-archive-month{margin:24px 0}.pk-archive-list{list-style:none;padding:0;margin:0;display:grid;gap:8px}.pk-archive-list a{display:flex;align-items:center;gap:12px;padding:10px 14px;background:var(--c-surface);border:1px solid var(--c-border);border-radius:10px}.pk-archive-list a:hover{border-color:var(--c-accent);text-decoration:none}.pk-archive-diff{color:var(--c-text-muted);font-size:.9rem;margin-left:auto}.pk-archive-done{color:#16a34a;font-weight:700}.pk-btn--on{background:var(--c-accent);color:#fff;border-color:var(--c-accent)}.pk-editboard .pk-ecell--lowconf{background:color-mix(in srgb,#f59e0b 30%,transparent)}.pk-hint{margin:14px auto;max-width:560px;background:var(--c-accent-soft);border:1px solid var(--c-accent);border-radius:12px;padding:14px 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