代码示例:(标识:cssref_default_fieldset)
<!DOCTYPE html>
<html>
<head>
<style>
/* 默认的 CSS 值 */
fieldset { 
  display: block;
  margin-left: 2px;
  margin-right: 2px;
  padding-top: 0.35em;
  padding-bottom: 0.625em;
  padding-left: 0.75em;
  padding-right: 0.75em;
  border: 2px groove (internal value);
}
</style>
</head>
<body>

<p>默认情况下,fieldset 元素会这样显示:</p>

<fieldset>
  <legend>Personalia:</legend>
  Name: <input type="text"><br>
  Email: <input type="text"><br>
  Date of birth: <input type="text">
</fieldset>

<p>自定义的 fieldset 元素(更改 padding-left 和 border):</p>

<fieldset style="padding-left:75px;border:5px solid green">
  <legend>Personalia:</legend>
  Name: <input type="text"><br>
  Email: <input type="text"><br>
  Date of birth: <input type="text">
</fieldset>

</body>
</html>
运行结果: