I want to replace the purple background on the Sensei template pages with a masthead. But when I add a masthead there is a large gap with the t3-header container. I want the masthead to go under the menu/logo/search bar and replace the large purple/pink gradient. I can change it by adding a background image to the t3 container -- but then I can only do that once and I want different images on that background on different pages.