asp gridview custom font-family not rendering inside iframe - iframe

Question

I am attempting to apply a custom font to the asp gridview that is nested in an iframe. We are using shtml to link pages together. The css was loaded by previous processing, however it was not being recognized forcing me to put a link on my page.
The font-face source items are duplicates of another css definition, so the paths are correct and work on the rest of the site. The background color is recognized, so I know the css is being evaluated. If another font is listed in the font-family, it is recognized and used.
I'm at a loss as to why the custom font that duplicates an existing css is not recognized. I'm focused on the issue relates to the iframe, but am unable to locate a resolution on this issue.
Thanks in advance
iframe statement used to load the asp page
<iframe id="ff" width="546px" height="200px" frameborder="0" scroll="yes" src="Career_JobListings.aspx"></iframe>
ASP code:
<%# Page Language="C#" AutoEventWireup="true" CodeFile="Career_JobListings.aspx.cs" Inherits="_Default" %>
<form runat="server" id="f1">
<div class="gridview">
<asp:sqldatasource id="jobListingsDS" runat="server"
selectcommand="SELECT JobID, JobName, JobDescription, FileLink FROM tblJobListings"
connectionstring="<%$ ConnectionStrings:dbConnectionString %>">
</asp:sqldatasource>
<h2>A listing of current job openings.</h2>
<asp:gridview id="grdJobListings" runat="server" autogeneratecolumns="false"
datasourceid="jobListingsDS"
onrowdatabound="jobListingsGridView_RowDataBound"
cssclass="gridview">
<Columns>
<asp:BoundField ItemStyle-Width="150px" ReadOnly="True" DataField="JobName" HeaderText="Job Name" SortExpression="JobName"/>
<asp:BoundField ItemStyle-Width="250px" DataField="JobDescription" HeaderText="Description" />
<asp:HyperLinkField HeaderText="Detailed Description" Text='Click for detailed description.' NavigateUrl='f<%# bind("FileLink")%>' Target="_blank" runat="server"/>
</Columns>
</asp:gridview>
</div>
</form>
CSS Information:
#font-face {
font-family: MuseoSlab;
src: url(fonts\Museo_Slab_900.otf);
src: url(fonts\Museo_Slab_900.ttf);
src: url(fonts\Museo_Slab_900.eot);
}
/* ASP usage */
.gridview {
font-family: MuseoSlab;
}
.gridview tr {
font-family: MuseoSlab;
background-color: #FF6600;
}

Answer 1

I had utilized a previous css and created a new one with the essential font and class items for my grid. It turns out that the resolution was a missing import.
The following was added to the top of the css and now the custom font is being applied.
#import url("framework.css");
Hope this helps others that encounter this issue.