Nebver mind, I did some trial and error and found how to do it. 🙂
Just one question is left. The mega menu is set to the right, how I change it to be in the centre?
Here is the code that my header-1 has:
<!-- HEADER BLOCK -->
<header id="t4-header-wrap" class="t4-header w-100">
<div class="t4-header-inner">
<div class="row no-gutters d-flex align-content-center flex-nowrap">
<div class="t4-megamenu-wrap">
<div class="container">
<div class="t4-megamenu-inner">
<div class="t4-navbar d-flex align-content-center">
<jdoc:include type="element" name="megamenu" />
</div>
<div class="t4-header-right d-flex align-items-center">
<jdoc:include type="element" name="offcanvas-toggle" />
<jdoc:include type="element" name="megamenu-toggle" />
<div class="d-none d-sm-flex">
<jdoc:include type="modules" name="head-actions" />
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</div>
</header>
<!-- // HEADER BLOCK -->