:root{
  --bg: hsl(210 40% 98%);
  --panel: hsl(0 0% 100%);
  --text: hsl(222 47% 11%);
  --muted: hsl(215 16% 47%);
  --accent: hsl(222 90% 56%);
  --accent-2: hsl(267 78% 58%);
  --ring: hsl(222 90% 56% / 0.35);
  --line: 2px;
  --thick: 3px;
  --cell: 90px;
  --radius: 16px;
  --shadow: 0 10px 25px hsl(220 40% 2% / .08), 0 2px 6px hsl(220 40% 2% / .06);
}

*{box-sizing:border-box}
html,body{height:100%}
body{
  margin:0;
  font: 16px/1.45 ui-sans-serif, -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, "Helvetica Neue", Arial;
  color:var(--text);
  background:
    radial-gradient(1200px 800px at -20% -10%, hsl(210 100% 95%), transparent),
    radial-gradient(1200px 800px at 120% 20%, hsl(280 100% 96%), transparent),
    linear-gradient(180deg, var(--bg), hsl(210 40% 97%));
}

.wrapper{
  max-width: 1100px;
  margin: 28px auto;
  padding: 0 20px 40px;
}

.header{
  display:flex; align-items:center; justify-content:space-between;
  margin-bottom:18px;
}

.brand{
  font-weight:800; font-size:22px; letter-spacing:.3px;
  display:flex; align-items:center; gap:10px;
}
.brand .dot{
  width:12px; height:12px; border-radius:999px;
  background:var(--accent);
  box-shadow:0 0 0 4px hsl(222 90% 56% / .15);
}

.toolbar{
  background:var(--panel);
  padding:12px 14px;
  border-radius: var(--radius);
  box-shadow: var(--shadow);
  display:flex; flex-wrap:wrap; gap:10px; align-items:center;
}

.toolbar .group{display:flex; gap:8px; align-items:center}

select, .btn, input[type="number"]{
  appearance:none;
  border: 1px solid hsl(220 14% 90%);
  background: hsl(0 0% 100%);
  color: var(--text);
  padding:10px 12px;
  border-radius: 12px;
  transition: box-shadow .2s, border-color .2s, transform .04s;
  font-weight:600;
}
select:hover, input[type="number"]:hover{border-color:hsl(220 14% 80%)}
select:focus, .btn:focus, input[type="number"]:focus{outline:0; box-shadow: 0 0 0 4px var(--ring); border-color: var(--accent)}

.btn{
  background: linear-gradient(180deg, hsl(222 90% 60%), var(--accent));
  color:white;
  border:none;
}
.btn.secondary{
  background: linear-gradient(180deg, hsl(267 78% 62%), var(--accent-2));
}
.btn.neutral{
  background: hsl(220 14% 96%);
  color:var(--text);
  border:1px solid hsl(220 14% 88%);
}
.btn:active{ transform: translateY(1px); }

.pill{
  display:inline-flex; align-items:center; gap:8px;
  padding:8px 12px; border-radius:999px; font-weight:700;
  background:hsl(220 14% 96%);
  border:1px solid hsl(220 14% 90%);
}
.pill strong{min-width:46px; display:inline-block; text-align:center}
#timer.danger{ background:hsl(0 85% 96%); border-color:hsl(0 80% 82%); }
#timer.danger strong{ color:hsl(0 77% 45%); }

.panel{
  margin-top:16px;
  background:var(--panel);
  border-radius:var(--radius);
  box-shadow: var(--shadow);
  padding:18px;
  display: flex;
  flex-direction: column;
  align-items: center;
}

.grid{
  --cell: 86px;
  display:grid;
  gap:0;
  border-radius:18px;
  overflow:hidden;
  box-shadow: var(--shadow);
  background: hsl(0 0% 100%);
  border: var(--thick) solid hsl(220 13% 60%);
}
@media (max-width: 720px){
  .grid{ --cell: 64px; }
}

.cell{
  position:relative;
  width:var(--cell); height:var(--cell);
  border: var(--line) solid hsl(220 13% 85%);
  background: hsl(var(--cage-h, 0) 65% 95% / .7);
  transition: background .2s, box-shadow .2s;
}

.cell .clue{
  position:absolute; top:6px; left:8px;
  font-size:14px; color:var(--muted); font-weight:800;
  user-select:none; pointer-events:none;
  opacity:.95;
  z-index:3; /* keep clue above input */
}

.cell input{
  position:absolute; inset:0; width:100%; height:100%;
  background:transparent; border:0; outline:0;
  font-size:34px; font-weight:800; text-align:center; color:var(--text);
  caret-color: hsl(0 0% 20%);
  z-index:1;
}
.cell input:focus{
  box-shadow: inset 0 0 0 3px hsl(0 0% 0% / .06);
  background: hsl(var(--cage-h, 0) 65% 95% / .85);
}

.cell.invalid{ background: hsl(0 85% 92% / .85) !important; }
.cell.ok{ box-shadow: inset 0 0 0 2px hsl(150 60% 40% / .35); }
.cell.good{ animation: pop .28s ease-out; }
@keyframes pop{ from{ transform: scale(.98); } to{ transform: scale(1); } }

.status{
  margin-top:12px; color:var(--muted); font-weight:700;
}
footer{ margin-top: 18px; color: hsl(220 10% 50%); font-size: 13px;}