z_element_plus/docs/.vitepress/vitepress/styles/overlay.scss

.overlay {
  position: fixed;
  top: 0;
  right: 0;
  bottom: 0;
  left: 0;
  background: rgba(0, 0, 0, 0.6);
  transition: opacity 0.5s;
  z-index: var(--overlay-z-index);
}