There are two things about this theme that cause errors in html validation that are easily remedied. In the event you’re unaware, they are:
In Includes > nav-bottom.php on line 20, there is a space missing before role=“navigation” after class=“fl-page-nav navbar navbar-default”
In classes > FLFonts.php, all of the font names that have spaces in them cause a validation error. This is fixed by adding a + sign instead of a space so that “Open Sans” becomes “Open+Sans”.