VS 2010 CSS Class Works On Deve Machine, But Not On Server

I have a menu that has a menu CSS class.

Code:

<asp:Menu ID="NavigationMenu" runat="server" CssClass="menu" EnableViewState="false" IncludeStyleBlock="false" Orientation="Horizontal">
CSS Code:
div.menu
{
    padding: 4px 0px 4px 8px;
}
 
div.menu ul
{
    list-style: none;
    margin: 0px;
    padding: 0px;
    width: auto;
}
 
div.menu ul li a, div.menu ul li a:visited
{
    background-color: #0f243e;
    border: 1px #4e667d solid;
    color: #dde4ec;
    display: block;
    line-height: 1.35em;
    padding: 4px 20px;
    text-decoration: none;
    white-space: nowrap;
}
 
div.menu ul li a:hover
{
    background-color: #000000;
    color: #ffffff;
    text-decoration: none;
}
 
div.menu ul li a:active
{
    background-color: #465c71;
    color: #cfdbe6;
    text-decoration: none;
}
On my development machine, I have no problems. It works great. But when I publish to my server, the CSS for only this class stops working. I have the same CSS for two sites and they've both stopped working.

So this makes me think it's something wrong with the server. I've reset IIS and cleared the IIS temp logs. I went back and made sure that the published files' markup was all good.

Anyone have any ideas?