CSS使用margin-bottom属性
的边距指定元素的底部边缘。它的长度值可以是％或auto。您可以尝试运行以下代码来设置下边距：
示例
<html>
<head>
</head>
<body>
<p style = "margin-bottom: 20px; border:2px solid red;">
This is a paragraph with a specified bottom margin .
</p>
<p style = "margin-top: 20%; border:2px solid green;">
This is another bottom with a specified top margin in percent
</p>
</body>
</html>