哈哈成功鸟
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312" />
<title>3.1页面头部制作练习题</title>
<style type="text/css">
/*在此定义相关样式，控制列表的显示形式*/
.difficult a
{
display:block;
width: 50px;
height: 30px;
line-height:30px;
text-align:center;
}
.difficult li
{
float:left;
list-style-type:none;
}
.difficult a:link,.difficult a:visited
{
text-decoration:none;
color:#000;
}
.difficult a:hover,.difficult a:active
{
text-decoration:none;
color:#FFF;
background-color:#be3948;
}
</style>
</head>