HTML validator returns warning for some sections

[sushidave]

Hey, thanks for this cool theme.

I noticed that the Nu HTML Checker by W3C returns a warning for sections of the Quark theme.

Examples:

Warning: Section lacks heading. Consider using h2-h6 elements to [add identifying headings to all sections](https://www.w3.org/wiki/HTML/Usage/Headings/Missing), or else use a div element instead for any cases where no heading is needed.
From line 45, column 21; to line 45, column 57
          <section class="navbar-section logo">↩

Warning: Section lacks heading. Consider using h2-h6 elements to [add identifying headings to all sections](https://www.w3.org/wiki/HTML/Usage/Headings/Missing), or else use a div element instead for any cases where no heading is needed.
From line 49, column 21; to line 49, column 65
          <section class="navbar-section desktop-menu">↩↩

Warning: Section lacks heading. Consider using h2-h6 elements to [add identifying headings to all sections](https://www.w3.org/wiki/HTML/Usage/Headings/Missing), or else use a div element instead for any cases where no heading is needed.
From line 43, column 13; to line 43, column 47
          <section class="container grid-lg">↩

It links to a document of Mozilla for further info which refers to the specifications for section elements.