:root {
  --bg: #0e1116;
  --panel: #161b22;
  --cell: #1c2230;
  --cell-border: #2a3242;
  --text: #e6edf3;
  --muted: #8b96a8;
  --accent: #ffb74d;
  --accent-glow: #ffb74d99;
  --line: #4fc3f7;
}

* { box-sizing: border-box; }

html, body {
  margin: 0;
  padding: 0;
  background: var(--bg);
  color: var(--text);
  font-family: ui-sans-serif, system-ui, -apple-system, "Segoe UI", Roboto, sans-serif;
  min-height: 100vh;
}

main {
  max-width: 480px;
  margin: 0 auto;
  padding: 1.25rem 1.5rem;
  text-align: center;
}

h1 {
  font-weight: 600;
  font-size: 1.75rem;
  margin: 0 0 1.25rem;
  letter-spacing: 0.02em;
}

.board-wrap {
  display: grid;
  grid-template-columns: 3rem 1fr 1fr 1fr 3rem;
  grid-template-rows: 1.5rem 1fr 1fr 1fr;
  gap: 0.4rem 0.5rem;
  width: min(420px, 95vw);
  margin: 0 auto;
}

.board-inner {
  grid-column: 2 / 5;
  grid-row: 2 / 5;
  position: relative;
  aspect-ratio: 1 / 1;
}

.board {
  position: relative;
  z-index: 1;
  display: grid;
  grid-template-columns: repeat(3, 1fr);
  grid-template-rows: repeat(3, 1fr);
  gap: 0.6rem;
  width: 100%;
  height: 100%;
}

.ev {
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 0.85rem;
  font-weight: 500;
  color: var(--muted);
  display: flex;
  align-items: center;
  justify-content: center;
  transition: color 0.15s, font-weight 0.15s;
}

.ev--row {
  grid-column: 1;
  justify-content: flex-end;
  padding-right: 0.55rem;
}

.ev--row[data-line="0"] { grid-row: 2; }
.ev--row[data-line="1"] { grid-row: 3; }
.ev--row[data-line="2"] { grid-row: 4; }

.ev--col {
  grid-row: 1;
  align-items: flex-end;
  padding-bottom: 0.45rem;
}

.ev--col[data-line="3"] { grid-column: 2; }
.ev--col[data-line="4"] { grid-column: 3; }
.ev--col[data-line="5"] { grid-column: 4; }

.ev--diag-maj {
  grid-row: 1;
  grid-column: 1;
  justify-content: flex-end;
  align-items: flex-end;
  padding: 0 0.55rem 0.45rem 0;
}

.ev--diag-min {
  grid-row: 1;
  grid-column: 5;
  justify-content: flex-start;
  align-items: flex-end;
  padding: 0 0 0.45rem 0.55rem;
}

.ev.recommended {
  color: var(--line);
  font-weight: 700;
}

.cell {
  background: var(--cell);
  border: 1px solid var(--cell-border);
  border-radius: 12px;
  font-family: ui-monospace, "SF Mono", Menlo, monospace;
  font-size: 2.75rem;
  font-weight: 600;
  color: var(--text);
  text-align: center;
  caret-color: transparent;
  transition: background 0.15s, box-shadow 0.2s, border-color 0.15s, transform 0.1s;
  outline: none;
  padding: 0;
  min-width: 0;
}

.cell:focus {
  border-color: var(--line);
  background: #1a2531;
  box-shadow: 0 0 0 3px #4fc3f755, inset 0 0 0 1px var(--line);
}

.cell.recommended {
  background: #2a2415;
  border-color: var(--accent);
  box-shadow: 0 0 0 2px var(--accent-glow), 0 0 18px 2px var(--accent-glow);
}

.cell.recommended:focus {
  background: #332a17;
  /* Both signals stack: orange glow (recommendation) + cyan inner ring (focus). */
  box-shadow: 0 0 0 2px var(--accent-glow), 0 0 18px 2px var(--accent-glow), inset 0 0 0 2px var(--line);
}

.line-overlay {
  position: absolute;
  inset: 0;
  width: 100%;
  height: 100%;
  pointer-events: none;
  z-index: 2;
  overflow: visible;
}

.line {
  stroke: var(--line);
  stroke-width: 0;
  stroke-linecap: round;
  opacity: 0;
  transition: opacity 0.25s, stroke-width 0.25s;
  filter: drop-shadow(0 0 6px var(--line));
  vector-effect: non-scaling-stroke;
}

.line.recommended {
  opacity: 0.9;
  stroke-width: 10;
}

.status {
  margin: 1.25rem 0 0.75rem;
  color: var(--muted);
  font-size: 0.95rem;
  min-height: 1.4em;
}


.status strong {
  color: var(--text);
  font-weight: 600;
}

.reset {
  background: transparent;
  color: var(--muted);
  border: 1px solid var(--cell-border);
  border-radius: 8px;
  padding: 0.45rem 1rem;
  font-size: 0.9rem;
  cursor: pointer;
  transition: color 0.15s, border-color 0.15s;
}

.reset:hover {
  color: var(--text);
  border-color: var(--muted);
}