body {
  margin: 0;
  background: #000;
  overflow: hidden;
  color: #3f3;
  font-family: monospace;
}

canvas {
  display: block;
  filter: drop-shadow(0 0 5px #3f3);
}

#ui {
  position: absolute;
  top: 10px;
  left: 10px;
  pointer-events: none;
  z-index: 10;
}

#startOverlay {
  position: fixed;
  inset: 0;
  display: flex;
  align-items: center;
  justify-content: center;
  background: rgba(0, 0, 0, 0.72);
  z-index: 20;
}

#startOverlay.hidden {
  display: none;
}

#startButton {
  background: #000;
  color: #3f3;
  border: 2px solid #3f3;
  font-family: monospace;
  font-size: 22px;
  padding: 14px 22px;
  cursor: pointer;
}