html, body {
  height: 100%;
  margin: 0;
}

body {
  background: black;
  display: flex;
  align-items: center;
  justify-content: center;
  flex-direction: column;
  color: white;
}

canvas {
  border: 1px solid white;
}

button {
  margin-top: 10px;
  padding: 10px 20px;
  background-color: green;
  color: white;
  border: none;
  cursor: pointer;
}

#score {
  position: absolute;
  top: 10px;
  right: 10px;
  font-size: 18px;
}