It may be due to the fact that the site has a legacy style skin, but in order to get the style I wanted to appear in the Category Menu module I had to make the following changes to categorymenu.ascx. I wasn't able to get the style to load directly from categorymenu.css.
<%@ control language="C#" autoeventwireup="true" inherits="Smith.DNN.Modules.CategoryMenu.CategoryMenu, App_Web_categorymenu.ascx.dd2a0b6c" %>
<link href="CategoryMenu.css" rel="stylesheet" type="text/css" />
<asp:TreeView
ID="tvCatMenu"
ExpandDepth="0"
PopulateNodesFromClient="true"
ShowLines="false"
ShowExpandCollapse="true"
ExpandImageUrl="~/DesktopModules/Smith.CategoryMenu/tv_expander.gif"
CollapseImageUrl="~/DesktopModules/Smith.CategoryMenu/tv_collapser.gif"
OnTreeNodePopulate="tvCatMenu_TreeNodePopulate"
OnSelectedNodeChanged="tvCatMenu_SelectedNodeChanged"
runat="server"
CssClass="SmithProdtext"/>
<style type="text/css">
<!--
body,td,th {
color: #000000;
}
a {
font-size: 10pt;
color: #000000;
font-weight: bold;
}
a:link {
text-decoration: none;
}
a:visited {
text-decoration: none;
}
a:hover {
text-decoration: none;
}
a:active {
text-decoration: none;
}
.style1 {font-size: 10pt}
-->
</style><table width="100%" border="0">
<tr>
<td> </td>
</tr>
</table>
<span class="style1"></span>