Hello.

In the file "md_megamenu.module" placed next string:

 $css = "@media(max-width: {$responsive_width}px){.awemenu-fix-mobile ul.awemenu{visibility:hidden;}}";

And this provide Total Validator Error E703, cause its not valid CSS.

Next strings works fine for us, so maybe you make some changes in this way.

 $css = "@media all and (max-width: {$responsive_width}px){.awemenu-fix-mobile ul.awemenu{visibility:hidden;}}";

Thanks!