Hello,

Your problem is resolved, now the CSS file is loading and your site looks just perfectly fine. Actually the WordPress Address and Site URL inside the general settings of your site, was not the same.

Screenshot for clarification: https://www.screencast.com/t/b2O1KoZk9y

About the Promo Banner issue you are using the banner images which is too much smaller in size. Try to upload the picture in higher resolution, so this image will not look blurry and distorted.

Screenshot for clarification: https://www.screencast.com/t/SeqNH5Y3NkD

Best Regards.