To achieve a header layout like this.
You can use this code to Custom CSS
/* Header layout */
.header-nav {
width: 100% !important;
padding-left: 0 !important;
border-top: 1px solid black;
padding-top: 10px;
margin-top: 10px;
}
.header-display-desktop {
flex-wrap: wrap;
}
nav.header-nav-list {
width: 100% !important;
justify-content: flex-start !important;
}
and use this code to Website Tools > Code Injection > Footer.
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.7.1/jquery.min.js"></script>
<script>
jQuery(document).ready(function($){
$('.header-display-desktop .header-nav').appendTo('.header-display-desktop');
})
</script>