html, body {
  margin: 0;
  padding: 0;
  height: 100%;
  background: #050508;
  overflow: hidden;
}

#stage {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
}

.start {
  position: fixed;
  left: 18px;
  bottom: 18px;
  width: 52px;
  height: 52px;
  border-radius: 999px;
  border: 1px solid rgba(255,255,255,0.15);
  background: rgba(255,255,255,0.06);
  color: rgba(255,255,255,0.85);
  font-size: 22px;
  cursor: pointer;
  backdrop-filter: blur(8px);
}

.start:active { transform: scale(0.98); }

#dot, .dot {
  position: fixed;          /* 关键：否则 left/top 不生效 */
  left: 0;
  top: 0;
  width: 8px;
  height: 8px;
  border-radius: 999px;
  background: rgba(255,255,255,0.55);
  pointer-events: none;
  transform: translate(-50%, -50%);
  z-index: 9999;
  opacity: 0.0;             /* 由 JS 改成 0.35 */
}