admin/public/plugins/element-plus/theme-chalk/src/skeleton.scss

@use 'mixins/mixins' as *;
@use 'mixins/var' as *;
@use 'common/var' as *;

@include b(skeleton) {
  @include set-component-css-var('skeleton', $skeleton);
}

@mixin skeleton-color() {
  background: linear-gradient(
    90deg,
    getCssVar('skeleton-color') 25%,
    getCssVar('skeleton-to-color') 37%,
    getCssVar('skeleton-color') 63%
  );
  background-size: 400% 100%;
  animation: #{$namespace}-skeleton-loading 1.4s ease infinite;
}

@keyframes #{$namespace}-skeleton-loading {
  0% {
    background-position: 100% 50%;
  }
  100% {
    background-position: 0 50%;
  }
}

@include b(skeleton) {
  width: 100%;
  @each $unit in (first-line, paragraph) {
    @include e($unit) {
      height: 16px;
      margin-top: 16px;
      background: getCssVar('skeleton-color');
    }
  }

  @include when(animated) {
    .#{$namespace}-skeleton__item {
      @include skeleton-color();
    }
  }
}