:root {
  --bg: #161616;
  --panel: #1f1f1f;
  --border: #3a3a3a;
  --text: #ffffff;
  --muted: #bbbbbb;
  --accent: #6c5ce7;
  --danger: #ff4d4d;
}

* { box-sizing: border-box; }

body {
  margin: 0;
  background: var(--bg);
  color: var(--text);
  font-family: 'Helvetica Neue', Helvetica, Arial, sans-serif;
}

.container {
  max-width: 640px;
  margin: 0 auto;
  padding: 16px;
}

header h1 {
  margin: 8px 0 4px;
  text-align: center;
  font-size: 30px;
  font-weight: 700;
}

.toolbar {
  display: flex;
  gap: 12px;
  justify-content: center;
  align-items: center;
  flex-wrap: wrap;
  margin: 14px 0;
}

button {
  background: #2a2a2a;
  color: var(--text);
  border: 1px solid var(--border);
  border-radius: 6px;
  padding: 6px 12px;
  font-size: 14px;
  cursor: pointer;
  font-family: inherit;
}

button:focus {
  outline: 2px solid var(--accent);
  outline-offset: 1px;
}

button:hover { background: #3a3a3a; }

.hud {
  display: flex;
  gap: 20px;
  justify-content: center;
  font-size: 14px;
  color: var(--muted);
}

.board-wrap {
  display: flex;
  justify-content: center;
  margin: 10px 0;
}

#board {
  border-radius: 10px;
  touch-action: none;
  cursor: crosshair;
}

.status {
  min-height: 24px;
  text-align: center;
  font-size: 14px;
  color: var(--muted);
}

.status.warn { color: var(--danger); }

.hidden { display: none !important; }

.overlay,
.modal-backdrop {
  position: fixed;
  inset: 0;
  background: rgba(0, 0, 0, 0.75);
  display: flex;
  align-items: center;
  justify-content: center;
  z-index: 10;
}

.card,
.modal-content {
  background: var(--panel);
  border: 1px solid var(--border);
  border-radius: 10px;
  padding: 24px 32px;
  max-width: 440px;
}

.card { position: relative; text-align: center; }
.card h2 { margin-top: 0; font-size: 28px; }
.card p { color: var(--muted); }
.card button { margin-top: 14px; padding: 8px 20px; }

.modal-content {
  position: relative;
  max-width: 560px;
  max-height: 82vh;
  overflow: auto;
}

.modal-content h2 {
  text-align: center;
  margin: 0 0 16px;
  font-size: 26px;
}

.modal-content h3 {
  text-align: center;
  margin: 20px 0 4px;
  font-size: 17px;
  font-weight: 700;
  letter-spacing: 0.6px;
  color: var(--text);
}

.modal-content p {
  margin: 8px 0;
  text-align: center;
  font-size: 15px;
  line-height: 1.5;
  color: #e8e8e8;
}

.close {
  position: absolute;
  top: 10px;
  right: 10px;
  background: transparent;
  border: none;
  color: var(--muted);
  font-size: 16px;
  padding: 4px 8px;
}

.demo {
  display: grid;
  gap: 4px;
  width: max-content;
  margin: 14px auto;
}

.demo > div {
  height: 48px;
  padding: 6px 10px;
  border: 2px solid #fff;
  font-size: 22px;
  font-weight: 700;
  color: #fff;
  line-height: 1;
}

.demo.conflict > div:nth-child(2) {
  border-color: var(--danger);
}