This is very common issue that when we deploy mvc4 application to server and found that css not loaded and style sheet link looks like
<link href="/Content/themes/base/css?v=myqT7npwmF2ABsuSaHqt8SCvK8UFWpRv7T4M8r3kiK01" rel="stylesheet"/>solution for this issue is very simple
<compilation debug="false" targetFramework="4.0">