/* [UX] 白底，消除瀏覽器載入時的閃爍感 */
body { margin: 0; padding: 0; background-color: #ffffff; }
@media (prefers-color-scheme: dark) {
  body { background-color: #121212; }
}

#app-splash {
  position: fixed; top: 0; left: 0; width: 100%; height: 100%;
  z-index: 9999;
  background-color: #ffffff;
  transition: opacity 0.3s ease-out; /* [Perf] 淡出 0.3s（JS 控制觸發） */
  display: flex;
  flex-direction: column;
  justify-content: center;
  align-items: center;
  pointer-events: none;
}
@media (prefers-color-scheme: dark) {
  #app-splash { background-color: #121212; }
}

/* [UX] Logo：浮出 → 停留 → 上浮淡出，全程 1.8s */
.splash-title {
  font-family: -apple-system, BlinkMacSystemFont, sans-serif;
  font-size: 2.5rem;
  font-weight: 700;
  color: #1a1a1a;
  letter-spacing: 1px;
  animation: logo-lifecycle 1.8s cubic-bezier(0.2, 0.8, 0.2, 1) forwards;
}
@media (prefers-color-scheme: dark) {
  .splash-title { color: #ffffff; }
}

@keyframes logo-lifecycle {
  0%   { opacity: 0; transform: translateY(30px); }   /* 起始：隱藏，偏下 */
  28%  { opacity: 1; transform: translateY(0); }      /* 0.5s：浮現到中央 */
  67%  { opacity: 1; transform: translateY(0); }      /* 1.2s：停留展示 */
  100% { opacity: 0; transform: translateY(-20px); }  /* 1.8s：上浮淡出 */
}