:root{--paper:#f6f5f0;--ink:#233c35;--muted:#78847e;--green:#1d6256;--line:#d9ddd5;--wash:#e9eee7;--selected:#c8e0d4;--error:#a34035;--surface:#fffefb;--surface-bright:#fff;--on-accent:#fff;--accent-fill:#1d6256;--accent-fill-hover:#174e44;--border-strong:#bacabd;--border-soft:#cbd4c8;--mini-line:#a6b5a4;--text-soft:#66766b;--text-strong:#526356;--text-faint:#8f9890;--note:#688176;--sage:#739c75;--focus:#b88e42;--selected-ring:#72a38e;--cell-line:#d6dcd4;--related:#f0f3ed;--same:#e0eade;--conflict-bg:#fbe7e0;--conflict-ring:#c67e69;--diagram-bg:#f6f7f2;--card:#eaece3;--pad-border:#dfe3d9;--tip-symbol:#9c956d;--warning-bg:#f0e5ca;--warning-ink:#6f5824;--hard-frame:#252a2d}
:root[data-theme=dark]{color-scheme:dark;--paper:#151b19;--ink:#e2e8e3;--muted:#94a199;--green:#7ec4ae;--line:#2f3a36;--wash:#22302b;--selected:#2d5447;--error:#f08b7d;--surface:#1c2421;--surface-bright:#24302b;--on-accent:#fff;--accent-fill:#2a7a69;--accent-fill-hover:#33907c;--border-strong:#44564e;--border-soft:#3a4943;--mini-line:#4d5e56;--text-soft:#a5b2aa;--text-strong:#bac6be;--text-faint:#7f8c85;--note:#98b8a8;--sage:#8fb891;--focus:#d8ab5c;--selected-ring:#5fa58c;--cell-line:#2d3834;--related:#1f2a26;--same:#27372f;--conflict-bg:#4a2621;--conflict-ring:#c67e69;--diagram-bg:#19211e;--card:#1f2925;--pad-border:#34423d;--tip-symbol:#c4b97f;--warning-bg:#3d331c;--warning-ink:#e8cf90;--hard-frame:var(--ink)}
*{box-sizing:border-box}html,body{overscroll-behavior-y:none}body{margin:0;background:var(--paper);color:var(--ink);font-family:Arial,Helvetica,sans-serif;-webkit-tap-highlight-color:transparent}button,a{touch-action:manipulation}button{font:inherit;cursor:pointer;color:inherit}button:disabled{opacity:.36;cursor:default}button:focus-visible,a:focus-visible{outline:3px solid var(--focus);outline-offset:3px}[hidden],.sprite{display:none!important}svg{width:22px;height:22px;fill:none;stroke:currentColor;stroke-width:1.65;stroke-linecap:round;stroke-linejoin:round}
main{width:100%;max-width:600px;margin:auto;padding:0 6px 24px}.masthead{height:100px;display:flex;align-items:center;border-bottom:1px solid var(--line);gap:20px}.brand{display:flex;align-items:center;gap:10px;font-size:25px;letter-spacing:-1.2px;text-decoration:none;color:var(--ink);font-weight:700;border:0;background:transparent;padding:4px 6px 4px 0;border-radius:8px}.brand-icon{width:34px;height:34px;border-radius:8px;flex-shrink:0}.brand:hover .brand-icon{box-shadow:0 0 0 3px var(--wash)}.brand-sub{letter-spacing:2.3px;font-size:10px;margin:8px 0 0 2px;font-weight:400}.header-actions{margin-left:auto;display:flex;align-items:center;gap:20px}.header-action{display:inline-flex;align-items:center;justify-content:center;gap:8px;padding:9px 12px;border:1px solid var(--border-strong);border-radius:5px;background:transparent;font-size:12px;white-space:nowrap}.header-action svg{width:19px;height:19px}
.tools{display:flex;justify-content:space-around;padding:0 4px 16px;gap:5px}.tools button{border:0;background:transparent;display:flex;flex:1;flex-direction:column;align-items:center;justify-content:center;gap:8px;font-size:11px;color:var(--text-soft);padding:8px 12px;border-radius:6px}.tools button:hover{background:var(--wash)}
.board-wrap{width:100%;aspect-ratio:1;display:grid;place-items:center;container-type:size}.board{display:grid;grid-template-columns:repeat(var(--n),minmax(0,1fr));grid-template-rows:repeat(var(--n),minmax(0,1fr));width:100%;height:100%;aspect-ratio:1;border:2px solid var(--ink);border-radius:3px;overflow:hidden;background:var(--surface);box-shadow:0 8px 30px #32463a05;user-select:none;-webkit-user-select:none;touch-action:none}
.cell{position:relative;border:0;border-right:1px solid var(--cell-line);border-bottom:1px solid var(--cell-line);background:var(--surface);font-size:29px;font-weight:400;padding:0;min-width:0;min-height:0;line-height:1;display:flex;align-items:center;justify-content:center;color:var(--green);user-select:none;touch-action:none}.cell.given{color:var(--ink);font-weight:500}.cell.given:after{content:"";position:absolute;bottom:4px;width:3px;height:3px;border-radius:50%;background:currentColor;opacity:.45}.cell.done{background:var(--tint)}.cell.conflict{color:var(--error);background:var(--conflict-bg)}.cell.hinted{box-shadow:inset 0 0 0 2px var(--selected-ring);z-index:1}.cell:focus-visible{outline:0;box-shadow:inset 0 0 0 3px var(--focus);z-index:2}
.board-footer{display:flex;justify-content:space-between;font-size:10px;color:var(--muted);padding:13px 0 21px;gap:5px}.saved-dot{display:inline-block;width:5px;height:5px;background:var(--sage);border-radius:50%;margin-right:4px}
.pad{display:grid;grid-template-columns:repeat(5,minmax(0,1fr));grid-template-rows:repeat(2,auto);gap:6px}.pad button{border:1px solid var(--pad-border);background:var(--surface);border-radius:5px;height:58px;min-width:0;display:flex;align-items:center;justify-content:center;font-size:25px;font-weight:400;color:var(--green);padding:0}.pad button:hover{background:var(--wash)}.pad button[aria-pressed=true]{background:var(--accent-fill);border:1px solid var(--accent-fill);color:var(--on-accent)}
.status{font-size:12px;line-height:1.5;color:var(--text-soft);text-align:center;min-height:36px;margin:16px 0 0}.status.error{color:var(--error)}.status.success{color:var(--green)}.next,.primary,.secondary{border:1px solid var(--border-soft);border-radius:5px;min-height:44px;padding:10px 14px;background:transparent;color:var(--ink);font:13px Arial,Helvetica,sans-serif}.primary,.next{background:var(--accent-fill);color:var(--on-accent);border-color:var(--accent-fill)}.next{width:100%;margin-top:8px}.tip{background:var(--wash);padding:12px 14px;border-radius:5px}.example{display:grid;grid-template-columns:repeat(3,35px);gap:2px;margin:16px auto;width:max-content}.example span{display:grid;place-items:center;height:35px;border:1px solid var(--border-strong);background:var(--wash)}
.eyebrow{font-size:10px;letter-spacing:1.8px;font-weight:700;color:var(--muted)}a{color:var(--green);overflow-wrap:anywhere}.sr-only,.difficulty-letter{position:absolute;width:1px;height:1px;padding:0;margin:-1px;overflow:hidden;clip-path:inset(50%);white-space:nowrap;border:0}
.difficulty-current{position:relative;width:40px;height:40px;padding:7px;flex-shrink:0}.difficulty-icon{fill:none;stroke:none;flex-shrink:0}.difficulty-icon .mountain-frame{fill:none;stroke:var(--ink);stroke-width:2;stroke-linejoin:round}.difficulty-icon .mountain-easy,.difficulty-icon .mountain-medium,.difficulty-icon .mountain-hard{display:none}[data-difficulty=easy] .mountain-easy,[data-difficulty=medium] .mountain-medium,[data-difficulty=hard] .mountain-hard{display:block}[data-difficulty=hard] .mountain-frame{stroke:var(--hard-frame);stroke-width:2.7}
.difficulty-options{display:grid;gap:8px;margin-top:18px}.difficulty-option{display:flex;align-items:center;gap:15px;width:100%;min-height:66px;padding:12px 15px;border:1px solid var(--line);border-radius:7px;background:transparent;text-align:left;color:var(--ink);justify-content:flex-start}.difficulty-option[aria-pressed=true]{background:var(--wash);border-color:var(--green)}.difficulty-option strong,.difficulty-option small{display:block}.difficulty-option strong{font-size:15px;font-weight:600}.difficulty-option small{font-size:11px;color:var(--muted);margin-top:4px}.difficulty-option .difficulty-icon{width:25px;height:25px;color:var(--green)}
dialog{border:1px solid var(--line);border-radius:12px;max-width:430px;width:calc(100% - 36px);background:var(--paper);color:var(--ink);box-shadow:0 20px 100px #122e3440;max-height:calc(100dvh - 40px);overscroll-behavior:contain}dialog::backdrop{background:#15352d66;backdrop-filter:blur(3px)}dialog#dialog{padding:0;overflow:hidden}.dialog-scroll{min-height:0;max-height:calc(100dvh - 40px);overflow:auto;overscroll-behavior:contain;padding:35px}.modal h2{font:32px Georgia,serif;margin:16px 0}.modal p,.modal li{font-size:14px;line-height:1.7;color:var(--text-soft)}.modal .actions{display:flex;flex-wrap:wrap;gap:10px;margin-top:25px}.modal .actions button{flex:1 1 100px}.dialog-close{position:absolute;z-index:2;top:8px;right:8px;display:flex;align-items:center;justify-content:center;width:44px;height:44px;padding:0;background:var(--paper);border:1px solid var(--line);border-radius:50%;color:var(--ink);font-size:26px}.dialog-close:hover{background:var(--wash)}
dialog#menu{position:fixed;inset:0 auto 0 0;margin:0;width:min(320px,86vw);max-width:none;height:100dvh;max-height:none;border:0;border-right:1px solid var(--line);border-radius:0 14px 14px 0;padding:calc(18px + env(safe-area-inset-top,0px)) 20px calc(20px + env(safe-area-inset-bottom,0px)) calc(20px + env(safe-area-inset-left,0px));overflow:auto}.menu-head{display:flex;align-items:center;gap:10px;margin-bottom:18px;position:sticky;top:calc(-18px - env(safe-area-inset-top,0px));z-index:2;background:var(--paper)}.menu-head .brand-icon{width:30px;height:30px;border-radius:7px}.menu-title{font:20px Georgia,serif}.menu-close{margin-left:auto;min-width:44px;width:44px;height:44px;border:1px solid var(--line);border-radius:50%;background:transparent;font-size:26px;line-height:1;color:var(--ink)}.menu-close:hover{background:var(--wash)}.menu-list{display:grid;gap:4px;padding:6px 0 16px;border-block:1px solid var(--line)}.menu-item{display:flex;align-items:center;gap:14px;width:100%;min-height:48px;padding:10px 12px;border:0;border-radius:7px;background:transparent;color:var(--ink);font-size:15px;text-align:left}.menu-item:hover{background:var(--wash)}.menu-item svg{color:var(--green);flex-shrink:0}.menu-switch{position:relative;margin-left:auto;width:38px;height:22px;border-radius:11px;background:var(--border-soft);flex-shrink:0}.menu-switch::after{content:"";position:absolute;top:3px;left:3px;width:16px;height:16px;border-radius:50%;background:var(--surface-bright)}[aria-checked=true] .menu-switch{background:var(--accent-fill)}[aria-checked=true] .menu-switch::after{transform:translateX(16px)}.menu-credits{padding-top:18px;font-size:13px;line-height:1.7;color:var(--text-soft)}.menu-credits p{margin:6px 0 18px}.menu-credits small{display:block}.menu-credits a{color:var(--green);text-underline-offset:3px;overflow-wrap:anywhere}
:root{--r0:var(--surface);--r1:var(--related);--r2:var(--wash);--r3:var(--same);--r4:var(--selected);--r5:var(--card);--r6:var(--related);--r7:var(--wash);--r8:var(--same);--r9:var(--card)}
@media(max-width:800px),(max-width:1000px) and (max-height:600px){
 :root{--mobile-top:env(safe-area-inset-top,0px);--mobile-bottom:env(safe-area-inset-bottom,0px);--mobile-left:env(safe-area-inset-left,0px);--mobile-right:env(safe-area-inset-right,0px);--mobile-width:calc(100vw - 12px - var(--mobile-left) - var(--mobile-right));--board-size:min(var(--mobile-width),max(0px,calc(100dvh - 252px - var(--mobile-top) - var(--mobile-bottom))))}
 main{height:100dvh;width:100%;max-width:none;margin:0;padding:var(--mobile-top) calc(6px + var(--mobile-right)) calc(4px + var(--mobile-bottom)) calc(6px + var(--mobile-left));display:grid;grid-template-columns:minmax(0,1fr);grid-template-rows:44px 44px var(--board-size) 16px 92px 32px;row-gap:4px;align-content:start}
 main>*{min-width:0;grid-column:1}.masthead{height:44px;gap:6px}.brand{font-size:19px;gap:6px;margin-right:auto;white-space:nowrap}.brand-icon{width:25px;height:25px;border-radius:6px}.brand-sub{font-size:7px;letter-spacing:1.4px;margin-top:4px}.header-actions{gap:6px}.header-action{padding:0;width:36px;height:36px;border:0;flex-shrink:0}.header-action svg{width:21px;height:21px}.difficulty-current{width:40px;height:40px;padding:7px}
 .tools{padding:0;gap:0;height:44px}.tools button{position:relative;display:flex;align-items:center;justify-content:center;flex-direction:row;height:44px;min-height:44px;min-width:0;margin:0;padding:0;border:0;border-radius:6px;background:transparent;color:var(--green)}.tools button>span{display:none}.tools button svg{width:22px;height:22px}
 .board-wrap{height:var(--board-size);aspect-ratio:auto;align-self:start}.board{width:var(--board-size);height:var(--board-size);max-width:100%}.cell{font-size:clamp(18px,calc(var(--board-size)/14),42px)}
 .board-footer{height:16px;padding:0;font-size:9px;align-items:center}.pad{height:92px;grid-template-rows:repeat(2,44px);gap:4px}.pad button{height:44px;min-height:44px;font-size:24px}.status{grid-row:6;height:32px;min-height:32px;margin:0;font-size:11px;line-height:16px;overflow:auto;overflow-wrap:anywhere}.next{grid-row:6;min-height:32px;height:32px;margin:0;font:12px/1.2 Arial,sans-serif;padding:4px 8px}.status:has(+.next:not([hidden])){visibility:hidden}
 .dialog-scroll{padding:52px 22px 28px;max-height:calc(100dvh - 24px - var(--mobile-top) - var(--mobile-bottom))}.modal{max-height:calc(100dvh - 24px - var(--mobile-top) - var(--mobile-bottom))}.modal h2{font-size:28px}
}
@media(max-width:360px){.masthead{gap:3px}.brand-sub{display:none}}
@media(prefers-reduced-motion:no-preference){button{transition:background .15s,box-shadow .15s}.menu-switch::after{transition:transform .15s}}