CSS display: block 示例

<style>
  .block-demo {
    background-color: #e8e8e8;
    padding: 10px;
  }
  .block-item {
    display: block;
    width: 200px;
    height: 60px;
    background-color: #2196F3;
    border: 1px solid #000;
    color: white;
    font-size: 18px;
    font-weight: bold;
    text-align: center;
    line-height: 60px;
    margin: 5px 0;
  }
</style>
<div class="block-demo">
  <div class="block-item">块级元素 1</div>
  <div class="block-item">块级元素 2</div>
  <div class="block-item">块级元素 3</div>
</div>