How to apply custom CSS using jQuery onto a mobile web application

How to apply custom CSS using jQuery onto a mobile web application

Hello,
I have created a mobile web application using MVC 4 Mobile web template. I am unable to apply custom CSS to even a simple <h6> or  <div> tag.
 
I have a custom CSS file in the content folder. I tried the following:
 
1. Adding the custom CSS file to the existing ~/Content/css bundle by giving the following:
bundles.Add(
new StyleBundle ( "~/Content/css" ).Include( "~/Content/MyCSSFile.css" ));
 
2. I also tried creating a new bundle:
bundles.Add(new StyleBundle("~/Content/MyBundleCSS").Include("~/Content/MyCSSFile.css"));
 
Both the above do not work.
 
Thanks
Dinesh.