element-plus/website/demo-styles/image.scss

@keyframes dot {
  0% {
    width: 0;
    margin-right: 1em;
  }
  100% {
    width: 1em;
    margin-right: 0;
  }
}

.demo-image {
  .block {
    padding: 30px 0;
    text-align: center;
    border-right: solid 1px var(--el-border-color-base);
    display: inline-block;
    width: 20%;
    box-sizing: border-box;
    vertical-align: top;
    &:last-child {
      border-right: none;
    }
  }

  .demonstration {
    display: block;
    color: var(--el-text-color-secondary);
    font-size: 14px;
    margin-bottom: 20px;
  }
}

.demo-image__placeholder,
.demo-image__error {
  @extend .demo-image;

  .block {
    width: 49%;
  }

  .#{$namespace}-image {
    width: 300px;
    height: 200px;
  }

  .image-slot {
    display: flex;
    justify-content: center;
    align-items: center;
    width: 100%;
    height: 100%;
    background: #f5f7fa;
    color: var(--el-text-color-secondary);
    font-size: 14px;
  }
}

.demo-image__placeholder {
  .dot {
    animation: dot 2s infinite steps(3, start);
    overflow: hidden;
  }
}

.demo-image__error {
  .image-slot {
    font-size: 30px;
  }
}

.demo-image__lazy {
  height: 400px;
  overflow-y: auto;

  .#{$namespace}-image {
    display: block;
    min-height: 200px;
    margin-bottom: 10px;

    &:last-child {
      margin-bottom: 0;
    }
  }
}