How to remove top margin on gantry-helium

Hi,

I am very new to Grav and without any experience con a CMS. I installed grav on a Raspberry Pi to be my home CMS and I would like to put a family photo as a header from the page top. I tried many options but my knowledge it is not enough 😦

Could you please help me?

Thanks a lot in advance,
Adrian

Is your site publicly accessible? Can you send a link to it?