css+html实现Skeleton Screen 加载占位图动画效果（带动画）

<div *ngFor="let item of [1,1,1],index as index" class="skeletonItem anim-opacity2 animation-delay{{index}}">
        <div class="skeletonText "></div>
        <div class="skeletonText" style="width:70%"></div>
        <div class="skeletonText" style="width:40%"></div>
      </div>

.skeletonItem {
      padding: 16px;
      border-bottom: 3px solid #eee;
    }

    .skeletonText {
      height: 16px;
      background: #e2e2e2;
      margin-top: 12px;
      border-radius: 4px;
    }

    .skeletonText:first-child {
      margin-top: 0;
    }
    .anim-opacity2 {
      animation: 1.5s opacity2 0s infinite;
    }
    .animation-delay0 {
      animation-delay: 0s;
    }
    .animation-delay1 {
      animation-delay: 0.5s;

    }
    .animation-delay2 {
      animation-delay: 1s;
    }

    @keyframes opacity2 {
      0% {
        opacity: 0.5
      }
      50% {
        opacity: 1;
      }
      100% {
        opacity: 0.5;
      }
    }