UPDATE:
We fixed this issue, you can update 2 files into your site:
1: File: [your_site_root]/templates/gk_decor/layouts/default.php
Line 96:
<div id="gkBg">
change to:
<div id="gkBg" class="<?php if($this->API->get('menu_fixed', 0)) echo 'header-sticky'; ?>">
2: File: [your_site_root]/templates/gk_decor/css/template.css
add this css rule:
html.j4 #gkBg.header-sticky {
padding-top: 0;
}
html.j4 #gkBg.header-sticky #gkHeader {
position: sticky;
}
This fix will be included in the next release of this template as well.
Regards