body {
  margin: 0;
  background: #111;
}

canvas {
  display: block;
  margin: auto;
  background: linear-gradient(#87ceeb, #4a90e2);
  border: 3px solid #333;
}

#menu, #pauseOverlay {
  position: absolute;
  top: 0;
  left: 0;
  width: 600px;
  height: 400px;
  margin: auto;
  right: 0;
  bottom: 0;
  background: rgba(0,0,0,0.75);
  color: white;
  font-family: sans-serif;
  text-align: center;
  z-index: 10;
  display: none;
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
}

#menu button, #pauseOverlay button {
  padding: 10px 20px;
  margin: 10px;
  font-size: 18px;
  border: none;
  border-radius: 8px;
  cursor: pointer;
  background-color: #00bcd4;
  color: white;
}