The setting for "Top menu style" is not applied in standard (desktop) mode of CSS3 Menu.
The responsive (tablet, phone) does work correctly (including top menu style).
I am using Protostart template.
Hi Rastislav Lubusky
Thanks for contacting and choosing our product,
About your problem, I checked your link and background color in the menu not displayed completely, You can add custom css in modules to fix the problem as follows;
In Modules go to tab Advanced
Custom CSS and add code:
#jux_megamenucss3 .megamenu .js-megamenu { background-color:#000;}
save and view results, hope is can help you