[Theme: Gallery] Banner/header absolute

Hi all,

I’m using the theme Gallery and this theme comes with a fixed header. However, this takes too many reading space so I want the header to be absolute (don’t stay in top when scrolling down). Can someone explain me how I can do this? I changed fixed to absolute in the CSS but then the website got messy ??

The website is wilmade.com.

Thank you very much in advance!

Regards,

Wilma