/* ====== 导航栏 logo 渐入渐出反色 ====== */
#nav .site-icon {
  transition: filter 0.6s ease, opacity 0.6s ease;
  filter: invert(1) brightness(200%);
  opacity: 1;
}

/* 滚动后恢复原色，渐变切换 */
#nav.scrolled .site-icon {
  filter: invert(0) brightness(100%);
  opacity: 1;
}