By default the Total theme doesn’t have a bottom margin under the header or navigation bar (headers two and three ) because the margin is under the main page header. But when you disable the page header there is no longer any space this is to allow customers to add content such as a slider right up against their content such as this demo.
If you disable the page header on a single page and want some space above the page simply insert the “Spacing” Visual Composer module at the top of the page to add some space.
If you disable the page header on all pages and want to add space manually to all of them you can use some CSS such as this:
body.page-header-disabled #main { padding-top: 40px; }
Here is the guide for adding custom css to your site.