使用带有double值的 border-style属性可以设置两行边框。您可以尝试运行以下代码以实现border-style属性：
<html> <head> </head> <body> <p style = "border-width:4px; border-style:none;"> This is a border with none width. </p> <p style = "border-width:4px; border-style:double;"> This is a border with two solid lines. </p> </body> </html>