Hello.
It's possible not to have the overlay effect that the splict vertical the headerbar in two zones, 50% darkner and 50lighter? I would like to have a uniform overlay over all image.

Thanks a lot.

Yes its possible.
Open the Top A Module with an Editor and remove the uk-overlay-background class

<div class="uk-overlay-panel uk-flex uk-flex-center uk-flex-middle uk-text-center">
<div style="padding:20px" class="border">
<h1 class="handwrite color">Bistro</h1>
<h3>Professional Joomla Template</h3>
<p><a class="scroll uk-button" href="#top-a">MORE</a></p>
</div>
</div>

Problem solved.