* { margin: 0; padding: 0; box-sizing: border-box; }
html, body {
  width: 100%; height: 100%;
  background: #04060f;
  overflow: hidden;
  font-family: system-ui, -apple-system, "Noto Sans TC", "Microsoft JhengHei", sans-serif;
  -webkit-user-select: none; user-select: none;
  -webkit-tap-highlight-color: transparent;
}
#stage {
  position: fixed; inset: 0;
  display: flex; align-items: center; justify-content: center;
}
#game {
  width: 100%; height: 100%;
  display: block;
  touch-action: none;
}
/* 直向提示（手機） */
#rotate {
  position: fixed; inset: 0;
  display: none;
  align-items: center; justify-content: center;
  text-align: center; line-height: 1.6;
  color: #cfe0ff; font-size: 24px; font-weight: 700;
  background: #04060f; z-index: 10;
}
/* 全螢幕按鈕 */
#fsbtn {
  position: fixed; top: 8px; right: 8px; z-index: 20;
  width: 40px; height: 40px; font-size: 20px;
  border-radius: 10px; border: 1px solid #3a5160;
  background: rgba(10,16,28,0.6); color: #cfe0ff; cursor: pointer;
}
@media (max-width: 900px) and (orientation: portrait) {
  #rotate { display: flex; }
  #fsbtn { display: none; }
}