body {
  margin: 0;
  font-family: Arial, sans-serif;
  background: #0B1C39;
  color: #fff;
  text-align: center;
}
#start-screen, #end-screen {
  margin-top: 150px;
}
#start-btn, #restart-btn, #mute-btn {
  padding: 10px 20px;
  margin: 10px;
  font-size: 18px;
  cursor: pointer;
  border: none;
  border-radius: 5px;
  background: #D4AF37;
  color: #0B1C39;
}
#hud {
  position: absolute;
  top: 10px;
  left: 10px;
  background: rgba(0,0,0,0.5);
  padding: 8px 16px;
  border-radius: 5px;
  font-size: 20px;
}
canvas {
  display: block;
  margin: 0 auto;
  background: linear-gradient(#123, #345);
  border: 2px solid #D4AF37;
}