body, html { margin: 0; }
body {
    background: #000;
}
.control-panel {
  position: fixed;
  top: 20px;
  left: 20px;
  background: rgba(0,0,0,0.8);
  color: white;
  padding: 12px;
  border: 1px solid #ff0;
  border-radius: 6px;
  font-family: sans-serif;
  z-index: 10;
}

.control-panel label {
  display: block;
  margin: 10px 0;
  font-size: 14px;
}

.control-panel input[type="range"],
.control-panel input[type="color"] {
  width: 100%;
}

canvas { position: fixed; touch-action: none; }