You can display a mega menu within an Elementor section using the Max Mega Menu widget.
Fix for Sticky Menu appearing behind content
Update: This issue is fixed in Elementor v1.5+. The following information is only relevant for users of Elementor < v1.5.
If you are using Max Mega Menu Pro, you may find the sticky menu appears below the other content on your page.
Go to Appearance > Customize > Additional CSS and enter the following:
Edit the page with Elementor and apply the following settings: