I know that people have had some trouble with undefined CssClass values when using partial classes in ASP.NET MVC. My project is not MVC, however, and I am including a .css file that is in the root folder of my project, yet a referenced class value still results in a warning in VS 2008.
In my .aspx file:
<html xmlns="http://www.w3.org/1999/xhtml" >
<head runat="server">
<!-- ... -->
<link media="all" href="~MyStyles.css" type="text/css" rel="stylesheet" />
</head>
<body id="bodyTag" vlink="#666666" alink="#666666" link="#666666" bgcolor="#ffffff" leftmargin="0" topmargin="0" runat="server">
<script type="text/javascript" language="javascript" src="~Scripts\Somecript_v1.js"></script>
<!-- form, table ... -->
<asp:TableRow>
<asp:TableCell ColumnSpan="4" CssClass="cellclass">
Then, in the same folder as the .aspx, in "MyStyles.css", I have defined:
.cellclass
{
border-right: #aeaeae 1px solid;
border-top: #aeaeae 1px solid;
font-weight: normal;
font-size: 11px;
/* etc. */
Yet I get the warning, "The class or CssClass value is not defined".