Styles.Render in MVC4
Solution 1:
It's calling the files included in that particular bundle which is declared inside the BundleConfig class in the App_Start folder.
In that particular case The call to @Styles.Render("~/Content/css") is calling "~/Content/site.css".
bundles.Add(new StyleBundle("~/Content/css").Include("~/Content/site.css"));
Solution 2:
Watch out for case sensitivity. If you have a file
/Content/bootstrap.css
and you redirect in your Bundle.config to
.Include("~/Content/Bootstrap.css")
it will not load the css.