:root{
  --bg:#101826;
  --bg-2:#1C2838;
  --line:#33465E;
  --line-strong:#5B7794;
  --ink:#EAF1FA;
  --muted:#8FA5BE;
  --given:#FFFFFF;
  --mine:#38BDF8;
  --wrong:#F87171;
  --amber:#F59E0B;
  --paper:#FFFFFF;
  --paper-ink:#101826;
  --paper-muted:#5D7084;
  --font:"Rubik", "Segoe UI", system-ui, sans-serif;
  color-scheme:dark;
}
*{box-sizing:border-box}
html,body{background:var(--bg)}
body{margin:0;color:var(--ink);font:16px/1.3 var(--font);padding-inline:10px;padding-block:8px 10px;-webkit-tap-highlight-color:transparent;overscroll-behavior:none}
.app{max-width:560px;margin-inline:auto;width:100%;grid-template-columns:minmax(0,1fr);min-height:calc(100dvh - 18px);display:grid;grid-template-rows:auto auto 1fr auto auto;gap:8px}

.bar{display:flex;align-items:center;justify-content:space-between;gap:10px;min-height:44px}
.back{color:var(--muted);text-decoration:none;font-weight:600;font-size:15px;white-space:nowrap}
.back:hover{color:var(--ink)}
.title{margin:0;font-weight:800;font-size:clamp(1.3rem,4vw,1.9rem);letter-spacing:.02em;white-space:nowrap}
.title span{color:var(--mine)}
.bar-actions{display:flex;gap:8px;align-items:center}
.icon-btn{width:42px;height:42px;border-radius:12px;border:0;background:var(--bg-2);color:var(--ink);display:grid;place-items:center;cursor:pointer;padding:0}
.icon-btn span{display:grid;place-items:center}
.icon-btn span[hidden]{display:none}
.icon-btn svg{width:22px;height:22px}
button{font:inherit;cursor:pointer}
.btn{border:0;border-radius:12px;background:var(--bg-2);color:var(--ink);font-weight:700;padding:10px 18px;box-shadow:0 4px 0 rgba(0,0,0,.4)}
.btn:active{translate:0 3px;box-shadow:0 1px 0 rgba(0,0,0,.4)}
.btn.small{padding:8px 14px;font-size:15px}
.btn.primary{background:var(--mine);color:#05283A;box-shadow:0 4px 0 #1C7FA8}
.btn.light{background:#DDE7F1;color:var(--paper-ink);box-shadow:0 4px 0 #B4C2D2}
:focus-visible{outline:3px solid var(--amber);outline-offset:2px}

.hud{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:6px}
.hud .cell{background:var(--bg-2);border-radius:10px;padding:4px 10px;display:grid;line-height:1.15;min-width:0}
.hud .cell span{font-size:10.5px;font-weight:600;letter-spacing:.09em;text-transform:uppercase;color:var(--muted)}
.hud .cell b{font-size:1.15rem;font-weight:700;font-variant-numeric:tabular-nums;white-space:nowrap;overflow:hidden;text-overflow:ellipsis}

.board-wrap{display:grid;place-items:center;min-height:0;min-width:0}
.board{width:min(100%,min(64vh,520px));max-width:100%;aspect-ratio:1;display:grid;grid-template-columns:repeat(9,1fr);background:var(--line);
  border:3px solid var(--line-strong);border-radius:8px;gap:1px;overflow:hidden;touch-action:manipulation}
.sq{position:relative;background:var(--bg-2);border:0;padding:0;color:var(--mine);font:600 clamp(1.1rem,4.6vw,1.9rem)/1 var(--font);
  display:grid;place-items:center;cursor:pointer;font-variant-numeric:tabular-nums}
.sq.given{color:var(--given);font-weight:700;background:#17222F}
.sq.b-r{margin-right:1px;box-shadow:2px 0 0 var(--line-strong)}
.sq.b-b{margin-bottom:1px;box-shadow:0 2px 0 var(--line-strong)}
.sq.b-r.b-b{box-shadow:2px 0 0 var(--line-strong),0 2px 0 var(--line-strong)}
.sq.peer{background:#213044}
.sq.given.peer{background:#1E2B3A}
.sq.same{background:#2A4258}
.sq.sel{background:#34536E;outline:2px solid var(--mine);outline-offset:-2px;z-index:2}
.sq.bad{color:var(--wrong)}
.sq.bad.flash{animation:shake .35s}
@keyframes shake{25%{translate:-3px}75%{translate:3px}}
.sq.done{animation:pop .5s}
@keyframes pop{40%{scale:1.18;color:var(--amber)}}
.notes{display:grid;grid-template-columns:repeat(3,1fr);width:100%;height:100%;font-size:clamp(.46rem,1.9vw,.72rem);color:var(--muted);font-weight:600}
.notes i{font-style:normal;display:grid;place-items:center}

.pad{display:grid;grid-template-columns:repeat(9,minmax(0,1fr));gap:5px}
.key{position:relative;aspect-ratio:1/1.15;min-width:0;border:0;border-radius:10px;background:var(--bg-2);color:var(--ink);font:700 clamp(1.1rem,4.6vw,1.6rem)/1 var(--font);
  box-shadow:0 3px 0 rgba(0,0,0,.45);display:grid;place-items:center}
.key:active{translate:0 2px;box-shadow:0 1px 0 rgba(0,0,0,.45)}
.key small{position:absolute;bottom:3px;right:5px;font-size:10px;font-weight:600;color:var(--muted)}
.key.full{opacity:.35;pointer-events:none}
.key.noting{background:#243A4F;color:var(--mine)}
.tools{display:grid;grid-template-columns:repeat(4,minmax(0,1fr));gap:6px}
.tool{border:0;border-radius:12px;background:var(--bg-2);color:var(--ink);font-weight:700;font-size:13.5px;padding:7px 0;display:grid;justify-items:center;gap:1px;box-shadow:0 3px 0 rgba(0,0,0,.45)}
.tool span{font-size:1.2rem;line-height:1}
.tool:active{translate:0 2px;box-shadow:0 1px 0 rgba(0,0,0,.45)}
.tool[aria-pressed="true"]{background:var(--mine);color:#05283A;box-shadow:0 3px 0 #1C7FA8}
.tool:disabled{opacity:.4;box-shadow:none;cursor:default}

.overlay{position:fixed;inset:0;z-index:20;display:grid;place-items:center;padding:16px;background:rgba(8,13,20,.86);overflow-y:auto}
.overlay[hidden]{display:none}
.sheet{width:100%;max-width:440px;background:var(--paper);color:var(--paper-ink);border-radius:20px;padding:20px 22px;display:grid;gap:14px;box-shadow:0 20px 50px rgba(0,0,0,.5)}
.sheet.center{text-align:center;justify-items:center;max-width:380px}
h2{margin:0;text-align:center;font-weight:800;font-size:1.9rem}
.help{margin:0;font-size:13.5px;color:var(--paper-muted);line-height:1.55}
.help b{color:var(--paper-ink)}
.help.small{font-size:12.5px;text-align:center}
.lbl{margin:2px 0 0;font-size:12px;font-weight:800;letter-spacing:.09em;text-transform:uppercase;color:var(--paper-muted)}
.levels{display:grid;gap:8px}
.levels button{border:0;border-radius:12px;padding:11px 16px;background:#EEF3F8;color:var(--paper-ink);font-weight:700;display:flex;justify-content:space-between;align-items:center;gap:10px;box-shadow:0 3px 0 #C9D5E1}
.levels button:active{translate:0 2px;box-shadow:0 1px 0 #C9D5E1}
.levels button b{font-size:1.05rem}
.levels button small{color:var(--paper-muted);font-weight:600;font-variant-numeric:tabular-nums}
.trophy{font-size:56px;line-height:1}
.end-title{margin:0;font-weight:800;font-size:1.6rem;text-wrap:balance}
.results{display:grid;grid-template-columns:1fr 1fr;gap:10px;width:100%}
.results div{background:#EFF3F8;border-radius:12px;padding:8px;display:grid}
.results span{font-size:10.5px;font-weight:700;letter-spacing:.09em;text-transform:uppercase;color:var(--paper-muted)}
.results b{font-size:1.7rem;font-variant-numeric:tabular-nums}
.lead{margin:0;color:var(--paper-muted);font-weight:600}
.row{display:flex;gap:10px;flex-wrap:wrap;justify-content:center}

@media (max-width:640px){
  .back-tx{display:none}
  .back{font-size:20px}
}
@media (prefers-reduced-motion:reduce){
  .sq.bad.flash,.sq.done{animation:none}
}