* { box-sizing: border-box; }

:root {
  --page-bg: #111;
  --text: #eee;
  --muted: #888;
  --board-bg: #000;
  --grid: #1a1a1a;
  --border: #444;
  --overlay-bg: rgba(0, 0, 0, 0.7);
  --kbd-bg: #222;
  --kbd-border: #555;
  --cell-outline: rgba(0, 0, 0, 0.5);
}

[data-theme="light"] {
  --page-bg: #f2f2f2;
  --text: #222;
  --muted: #666;
  --board-bg: #fff;
  --grid: #e6e6e6;
  --border: #bbb;
  --overlay-bg: rgba(255, 255, 255, 0.8);
  --kbd-bg: #fff;
  --kbd-border: #bbb;
  --cell-outline: rgba(0, 0, 0, 0.25);
}

body {
  margin: 0;
  min-height: 100vh;
  padding-bottom: 16px;
  display: flex;
  flex-direction: column;
  align-items: center;
  background: var(--page-bg);
  color: var(--text);
  font-family: system-ui, sans-serif;
}

header {
  display: flex;
  align-items: center;
  gap: 16px;
  margin: 20px 0 12px;
}

h1 { margin: 0; letter-spacing: 4px; }

#theme-toggle {
  padding: 4px 10px;
  border: 1px solid var(--border);
  border-radius: 4px;
  background: var(--kbd-bg);
  color: var(--text);
  font: inherit;
  font-size: 13px;
  cursor: pointer;
}

h2 {
  margin: 0 0 4px;
  font-size: calc(13px * var(--scale, 1));
  text-transform: uppercase;
  color: var(--muted);
}

.game { display: flex; gap: calc(20px * var(--scale, 1)); }

.board-wrap { position: relative; }

#board {
  display: block;
  background: var(--board-bg);
  border: 2px solid var(--border);
}

.overlay {
  position: absolute;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: var(--overlay-bg);
  font-size: calc(20px * var(--scale, 1));
  text-align: center;
}

.overlay.hidden { display: none; }

.panel { width: calc(160px * var(--scale, 1)); }

.panel section { margin-bottom: calc(20px * var(--scale, 1)); }

.panel p {
  margin: 0 0 calc(12px * var(--scale, 1));
  font-size: calc(22px * var(--scale, 1));
  font-weight: bold;
}

#next { background: var(--board-bg); border: 2px solid var(--border); }

.controls ul { list-style: none; padding: 0; margin: 0; font-size: calc(13px * var(--scale, 1)); line-height: 1.9; }

kbd {
  padding: 1px 5px;
  border: 1px solid var(--kbd-border);
  border-radius: 3px;
  background: var(--kbd-bg);
  font-family: inherit;
}