a标签，伪类选择器link不生效问题

 1 <style>
 2     a:link{
 3         color: green;
 4         background-color: white;
 5     }
 6     a:visited{
 7         color: orange;
 8     }
 9     a:hover{
10         color: hotpink;
11     }
12     a:active{
13         color:red;
14     }
15 </style>
16 
17 <a href="https://www.baidu.com/link?url=Syf2ZG1bhG6PTNURfjYpfwqre_gxInlHI31ubuck7Gy&wd=&eqid=d9d0d3a30010ef250000000260db064e" target="_blank">百度</a>