How do I fix the missing top 1/2 inch of the content box? I made a number of formatting changes to several basic pages using a Bootstrap-based premium theme. The changes accomplished what I wanted but I subsequently noticed that, when I visited the site as an anonymous user, the top roughly 1/2 inch of the content part of each page is not displayed. It's as if the top of the page is hidden behind the horizontal menu bar at the top of the page rather than appearing correctly a 1/2 inch down. 

I backed out all the changes I could remember making but it's still broken. It displays correctly when logged in as either admin or an authenticated user. I don't know how to even begin troubleshooting this issue. Can anyone point me in the right direction?
The body class in the custom-media.css is defining margin-top: 90px for the fixed header, you will need to increase this to match the size of your header. 

You may need to include media queries to account for reactive menu changes.

It probably works when you are logged in because either the admin toolbar is modifying the margin or there is a rule specifically for being logged in that assumes the toolbar but you don't have it enabled.