* { margin: 0; padding: 0; box-sizing: border-box; }

html, body {
  width: 100%;
  height: 100%;
  background: #000;
  overflow: hidden;
  font-family: -apple-system, "Helvetica Neue", Arial, sans-serif;
  color: #fff;
}

/* canvas 全螢幕，無框 */
#stage {
  position: fixed;
  inset: 0;
  width: 100vw;
  height: 100vh;
  display: block;
  background: #000;
  image-rendering: -webkit-optimize-contrast;
}

/* 隱藏 video（只供 canvas 取畫面用） */
video {
  position: absolute;
  width: 1px;
  height: 1px;
  opacity: 0;
  pointer-events: none;
  left: -9999px;
  top: -9999px;
}

audio { display: none; }

/* 啟動畫面 */
#startScreen {
  position: fixed;
  inset: 0;
  display: flex;
  flex-direction: column;
  align-items: center;
  justify-content: center;
  background: #000;
  z-index: 99;
  gap: 18px;
  transition: opacity 0.6s ease;
}
#startScreen.hidden {
  opacity: 0;
  pointer-events: none;
}
#startBtn {
  padding: 20px 64px;
  font-size: 22px;
  font-weight: 700;
  letter-spacing: 6px;
  background: linear-gradient(135deg, #b14bff, #ff3eb5);
  color: #fff;
  border: none;
  border-radius: 50px;
  cursor: pointer;
  box-shadow: 0 0 40px rgba(177, 75, 255, 0.6);
  transition: transform 0.2s, box-shadow 0.2s;
}
#startBtn:hover {
  transform: scale(1.05);
  box-shadow: 0 0 60px rgba(255, 62, 181, 0.85);
}
#startScreen p {
  opacity: 0.6;
  font-size: 12px;
  letter-spacing: 4px;
}