Top Right Banner Style
#topright {
position: absolute;
right: 0;
top: 0;
display: block;
height: 125px;
width: 125px;
background: url(TRbanner.gif) no-repeat;
text-indent: -999em;
text-decoration: none;}

Top Left Banner Style
#topleft {
position: absolute;
left: 0;
top: 0;
display: block;
height: 125px;
width: 125px;
background: url(TLbanner.gif) no-repeat;
text-indent: -999em;
text-decoration: none;}

查看效果http://www.exploding-boy.com/images/banners/banners.html