It is fairly simple to make a template be above all the content for a design.
Inside of the template is a unique component called "Child Template Content" which you can find via the Sidebar. Open the inspector for that component and find the z-index under "Position + Size". Delete the value in the z-index so it turns to a gray 0 and refresh your design. It should cause all content to be above the design.
One thing to note that is if you use a background in your template, it will also be above the content on the design.