If you haven't already, it might be a good idea to contact Support to upgrade your site to the fully responsive Website Builder. This upgrade allows you to configure your site's design on the fly. We've got separate articles on each of the tabs for Website Builder. To adjust the elements of your design using Website Builder simply...
1.) Hover over your photo on the top right > Click on Settings.
2.) Scroll Down to and click on Website Builder.
We've separated each tab into it's own article.
For help with Branding see this article.
For help with Site Layout see this article.
For help with Homepage Design see this article.
For help with Card Options see this article.