#dh
{
width:1003px;
height:36px;
background-image:url(images/mmain_03.gif)
}
#dh li
{
height:30px;
width:110px;
float:left;
list-style:none;
text-align:center;
margin:7px;
padding:5px;
}
#dh li a:link
{
font-size:16px;
font-weight:bold;
color:#FFFFFF;
text-decoration:none;
}
#dh li a:visited
{
font-size:16px;
font-weight:bold;
font-family:"Arial Black";
color:#FFFFFF;
text-decoration:none;
}
#dh li a:hover
{
font-size:16px;
font-weight:bold;
color:#FF0000;
text-decoration:underline;
}

这里应该主要css顺序:a:hover应该放在最后