:root{
  --bg:#0F1A24;
  --bg-2:#1A2836;
  --tile:#22323F;
  --tile-2:#2B3F4F;
  --pipe:#64798C;
  --water:#22D3EE;
  --water-2:#0EA5C6;
  --ink:#E8F4FA;
  --muted:#8AA3B5;
  --amber:#F59E0B;
  --paper:#FFFFFF;
  --paper-ink:#0F1A24;
  --paper-muted:#5B7183;
  --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%;min-height:calc(100dvh - 18px);display:grid;grid-template-rows:auto auto 1fr auto;grid-template-columns:minmax(0,1fr);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);white-space:nowrap}
.title span{color:var(--water)}
.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(--water);color:#06303A;box-shadow:0 4px 0 var(--water-2)}
.btn.light{background:#DCE8EF;color:var(--paper-ink);box-shadow:0 4px 0 #B3C3CE}
.btn.big{font-size:1.1rem;padding:12px 26px;width:100%}
: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{display:grid;gap:3px;background:var(--bg-2);padding:6px;border-radius:14px;box-shadow:inset 0 0 0 2px rgba(255,255,255,.05);
  width:min(100%,min(72vh,520px));touch-action:manipulation}
.sq{position:relative;aspect-ratio:1;border:0;padding:0;border-radius:8px;background:var(--tile);display:grid;place-items:center;cursor:pointer;overflow:hidden;min-width:0}
.sq:hover{background:var(--tile-2)}
.sq svg{width:100%;height:100%;display:block;transition:rotate .18s ease-out}
.sq .pipe{stroke:var(--pipe);stroke-width:13;stroke-linecap:round;fill:none;transition:stroke .25s}
.sq.wet{background:#1C3442}
.sq.wet .pipe{stroke:var(--water);filter:drop-shadow(0 0 5px rgba(34,211,238,.75))}
.sq.src{background:#123B46}
.sq.src .pipe{stroke:var(--water)}
.sq .tank{fill:var(--water);opacity:.95}
.sq.spin svg{rotate:var(--rot)}
.sq.hint{animation:hint 1s ease-in-out 2}
@keyframes hint{50%{background:#3C5A2E}}
.board.done .sq.wet .pipe{animation:pulse 1.2s ease-in-out 2}
@keyframes pulse{50%{stroke:#A5F3FC}}

.tools{display:grid;grid-template-columns:1fr 1fr;gap:6px}
.tool{border:0;border-radius:12px;background:var(--bg-2);color:var(--ink);font-weight:700;font-size:14px;padding:9px 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)}
.hintline{grid-column:1 / -1;margin:0;text-align:center;color:var(--muted);font-size:12.5px;font-weight:500;min-height:1.2em}

.overlay{position:fixed;inset:0;z-index:20;display:grid;place-items:center;padding:16px;background:rgba(6,12,18,.86);overflow-y:auto}
.overlay[hidden]{display:none}
.sheet{width:100%;max-width:430px;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}
h2 span{color:var(--water-2)}
.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:#EDF3F7;color:var(--paper-ink);font-weight:700;display:flex;justify-content:space-between;align-items:center;gap:10px;box-shadow:0 3px 0 #C6D4DE}
.levels button:active{translate:0 2px;box-shadow:0 1px 0 #C6D4DE}
.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:#EFF4F8;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 svg{transition:none}
  .sq.hint,.board.done .sq.wet .pipe{animation:none}
}