Here is a template with a fixed background image, which also will work on phone-size screens. I found the css for it on the web and have recreated it in RFF. It should be quite easy to do in RBB too. What you see is one row with a HTML element, which has been made full width and is holding the background image, and another row for the contents. Because of the fixed position of the background image, the contents row slides up on top of it. The image is from Kiel, Germany, where spring has come a bit further than here in Norway ;)
You have to save this as a theme since it consists of two rows, or possibly save each row as a separate component and just place them in a new project as they are here.
The rest of the text is just filling, so as to make it scroll on phone size screens.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta.
Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer nec odio. Praesent libero. Sed cursus ante dapibus diam. Sed nisi. Nulla quis sem at nibh elementum imperdiet. Duis sagittis ipsum. Praesent mauris. Fusce nec tellus sed augue semper porta. Mauris massa. Vestibulum lacinia arcu eget nulla. Class aptent taciti sociosqu ad litora torquent per conubia nostra, per inceptos himenaeos.