You make the header and the toptext background transparent 

Hi, I don't think it will be enough to do as John told you: if you don't have any image under the Header, even if you set it as transparent, it will always appear white by default. Read here if it can help you if you want to get a result identical to that indicated by you in the link above:
https://helpcenter.websitex5.com/de/post/226851

further information here:
https://helpcenter.websitex5.com/de/post/227752