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：
<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>