Image not "setting" properly?

[ricoontheradio]

The "Tell A Friend" button is not displaying correctly for some reason, and I have no idea how to fix this. This image comes from the .css which I'm not familiar with. I know how to access it, and where the image is, but not sure how to fix this issue:

 

Site: http://www.allpopradio.com

 

Here is the code for that image:

 

.nav1, .nav1 a, .nav1 a:visited, .nav1Current a {

display: block;

width: 128px;

height: 35px;

background: url(images/nav_tellfriend_off.gif);

}

 

.nav1 a:hover, .nav1 a:active {

background: url(images/nav_tellfriend_on.gif);

}

 

.nav1Current, .nav1Current a, .nav1Current a:visited, .nav1Current a:active, .nav1Current a:hover {

background: url(images/nav_tellfriend_on.gif);

}

 

Ideas/thoughts on how to fix? Thank you in advance for any help.

[ricoontheradio]

NOTE: This only displays wrong in Firefox. IE is fine.

[chronister]

Well, this has nothing to do with PHP... this is the PHP Help board......

 

But the image next to it is 124x35 and this image is 128x35. Dunno if that extra 4 pixels would do it, but it may.