body {
  margin: 0;
  background: black;
  overflow: hidden;
  font-family: Arial, sans-serif;
  color: white;
}

#hud {
  position: fixed;
  top: 20px;
  left: 20px;
  background: rgba(0,0,0,0.5);
  padding: 15px 20px;
  border-radius: 8px;
  border: 1px solid rgba(255,255,255,0.2);
  z-index: 20;
}

#controls {
  margin-top: 10px;
}

button {
  margin-right: 8px;
  padding: 8px 14px;
  background: #222;
  color: white;
  border: 1px solid #555;
  cursor: pointer;
}

button:hover {
  background: #333;
}

#universe {
  position: fixed;
  top: 0;
  left: 0;
  width: 100vw;
  height: 100vh;
  z-index: -1;
}