ul/li-css style applies to content AND style-combobox?

Hello,
I have to modify the CSS style for ul and li (using background-image instead of any list-style-image).
But the modification (ul li) also applies to the stylesSet-combobox!
How can I change that?
thanks in advance
Michael Mo

PS: here is the css-code I added to _samples/assets/output_xhtml.css

ul {
   list-style-type: none;
    list-style-position: none;
   margin: 0pt 0pt 0pt 0pt;
   padding: 0pt 0pt 0pt 0pt;
   color: #80000;
}

ul li {
   font-family: Times New Roman, Helvetica, Helvetica Narrow, Arial, Verdana, sans-serif;
   font-size: 11pt;
   padding: 6pt 0pt 0pt 16pt;
   background-image: url("http://a.cksource.com/e/1/gfx/icon.png");
   background-position: 0.0em 0.4em;
   background-repeat: no-repeat;
   color: #ff0000;
}