#board-wrap {
  position: relative;
  display: flex;
  justify-content: center;
}

#gameCanvas {
  display: block;
  /* 172px = site-header(44) + game header(70) + toolbar(42) + gaps(16) */
  width: min(400px, 96vw, calc(100dvh - 172px));
  aspect-ratio: 1;
  border-radius: var(--radius-md);
  box-shadow: var(--shadow-lg);
  touch-action: none;
  cursor: pointer;
}

#msg-overlay {
  position: absolute;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.76);
  color: #fff;
  font-size: 1.3rem;
  font-weight: bold;
  border-radius: var(--radius-md);
  gap: 14px;
  text-align: center;
  padding: 20px;
}

#msg-overlay[hidden] { display: none; }