body { margin: 0; overflow: hidden; background: #eef; }
canvas { display: block; margin: auto; background: #ddf; }
#timer {
  position: absolute;
  top: 10px;
  left: 10px;
  font-size: 24px;
  font-family: sans-serif;
  background: rgba(255,255,255,0.8);
  padding: 6px 12px;
  border-radius: 8px;
}