* { margin: 0; padding: 0; box-sizing: border-box; }
html, body { width: 100%; height: 100%; overflow: hidden; background: #1a1a1a; touch-action: none; }
canvas { display: block; width: 100%; height: 100%; cursor: crosshair; }

#ui-overlay {
  position: fixed;
  top: 0; left: 0;
  width: 100%; height: 100%;
  pointer-events: none;
  z-index: 10;
}

#fullscreen-btn, #mute-btn {
  position: fixed;
  pointer-events: auto;
  background: rgba(255,255,255,0.08);
  border: 2px solid rgba(255,255,255,0.2);
  color: #fff;
  font-size: 18px;
  width: 40px;
  height: 40px;
  border-radius: 50%;
  cursor: pointer;
  display: flex;
  align-items: center;
  justify-content: center;
  transition: background 0.2s, border-color 0.2s;
  font-family: monospace;
  z-index: 20;
}
#fullscreen-btn:hover, #mute-btn:hover {
  background: rgba(255,255,255,0.15);
  border-color: rgba(255,255,255,0.4);
}
#fullscreen-btn {
  top: 12px;
  right: 12px;
}
#mute-btn {
  top: 12px;
  right: 60px;
}