Hi there,
Looks like you have Contained checked in the Page Builder Container for the pages that have the wrong/zero padding:
https://docs.generatepress.com/article/page-builder-container/
For the shadows appearing different, one of the pages is using Elementor which is blocking the shadow a bit. Try this additional CSS:
.elementor-page .main-navigation {
margin-bottom: 5px;
}
For the site loading issue, is your site autoptimize setting exactly the same as in here?
https://generatepress.com/fastest-wordpress-theme/
I don’t see FontAwesome icon being added in the footer in any pages?