我们可以使用 border 属性来设置带边框的按钮组 - 在线编辑器

          <!DOCTYPE html>
<html>
<head>
  <meta charset="utf-8">
  <style>
    .button {
      background-color: #4CAF50;
      /* Green */
      border: 1px solid green;
      color: white;
      padding: 15px 32px;
      text-align: center;
      text-decoration: none;
      display: inline-block;
      font-size: 16px;
      cursor: pointer;
      float: left;
    }

    .button:hover {
      background-color: #3e8e41;
    }
  </style>
</head>
<body>

  <h2>带边框按钮组</h2>
  <p>Add borders to create a bordered button group:</p>

  <button class="button">Button</button>
  <button class="button">Button</button>
  <button class="button">Button</button>
  <button class="button">Button</button>

  <p style="clear:both"><br>记住要清除浮动，否则下一个 p 元素的按钮也会显示在同一行。</p>

</body>
</html>
        