html, body {
  margin: 0;
  padding: 0;
  width: 100%;
  height: 100%;
  overflow: hidden;
  background: #111;
}

canvas {
  display: block;
  width: 100%;
  height: 100%;
}

#ui {
  position: fixed;
  bottom: 16px;
  right: 16px;
  display: flex;
  flex-direction: column;
  gap: 8px;
  z-index: 10;
}

#ui button {
  width: 40px;
  height: 40px;
  border-radius: 50%;
  border: 1px solid rgba(255, 255, 255, 0.14);
  background: rgba(12, 12, 12, 0.72);
  color: rgba(255, 255, 255, 0.80);
  font-size: 18px;
  line-height: 1;
  cursor: pointer;
  backdrop-filter: blur(6px);
  transition: background 0.15s, transform 0.1s;
}

#ui button:hover  { background: rgba(255, 255, 255, 0.18); transform: scale(1.1); }
#ui button:active { transform: scale(0.92); }