Sobald ich ein UI-Icon hinzufüge, wird der Button zerschossen. So schauts aus:

Hier, ich hab's in eine eigene Html gepackt, um das Problem zu analysieren:
[url:http://www.maleska.de/tmp/Testbutton/Testbutton.html]
Der Quellcode:
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<meta http-equiv="content-type" content="text/html; charset=windows-1250">
<meta name="generator" content="PSPad editor, www.pspad.com">
<title></title>
<style type="text/css">
.ui-icon {
background-image: url(ui-icons_ffffff_256x240.png);
display:block;
text-indent: -99999px;
overflow: hidden;
background-repeat: no-repeat;
width:16px;
height:16px;
}
.ui-icon-triangle-1-n {
background-position: 0 -16px;
}
div#EditContent {
float: left;
margin-right: 10px;
font-size: 0.8em;
font-family: Arial, Helvetica, sans-serif;
font-weight: normal;
text-transform: uppercase;
}
div#EditContent a {
padding: 3px 8px 3px 8px;
background: url(ui-bg_highlight-soft_25_2f3865_1x100.png) 50% 50% repeat-x;
background-color: #4A4A6F;
color: #fff;
border: solid 1px #6A6A8F;
-moz-border-radius: 2px; -webkit-border-radius: 2px;
}
div#EditContent a:hover {
background: url(ui-bg_highlight-soft_60_3f487d_1x100.png) 50% 50% repeat-x;
border: 1px solid #8d95cc;
background-color: #FFCC00;
color: #000;
}
</style>
</head>
<body style="background-color:black;">
<div id="EditContent" >
<a href="#" style="margin-left:130px;">Nur Text</a>
</div>
<body style="background-color:black;">
<div id="EditContent" >
<a href="#" style="margin-left:130px;"><span class="ui-icon ui-icon-triangle-1-n"></span>Mit Icon</a>
</div>
</body>
</html>