Ok I have removed my css, if you could remove all of your CSS, copy and paste it somewhere. Then save the changes and let me know if the problems are fixed. It looks like it could be something in your custom css causing the issues
guess there would be a General Problem with the full width alt Background? I think I will not use the alt Background until there is a solution for it.
have you put your css only in the custom css box?
thank you best regards
Yes my CSS is no longer there, on our installations the alt background works fine. Therefore for it to behave like it is doing on your site must be down to the customisations you have made