I recently came across a very annoying "feature" when developing an MVC5 site, and it took a few hours to resolve.

The white/blank above the navbar is the issue. To resolve this I added a margin-top: -50px in the Header of the _layouts view and all other _layouts that I had developed. Now it looks like this.

<style>
        body {
            margin-top: -50px;
        }
</style>