转：http://www.cnblogs.com/Bear-Study-Hard/archive/2010/03/22/1691641.html
在core.css文件中
.ms-SpLinkButtonActive a,.ms-SpLinkButtonActive a:hover{
color:#000000;
text-decoration:none;
}
.ms-SPLink A:link,.ms-SPLink A:visited
{
color:#2A4666;
text-decoration:none;
}
链接后面的黄色背景
.ms-menubuttonactivehover,.ms-buttonactivehover{
margin:0px 1px 0px 1px;
padding:3px 7px 4px 7px;
background-image:url("/_layouts/images/menubuttonhover.gif");
line-height:16px;
border:solid 1px #6f9dd9;
cursor:pointer;
}
那个黑色向下箭头的位置：
C:\Program Files\Common Files\Microsoft Shared\web server extensions\12\TEMPLATE\IMAGES\MENUDARK.GIF
