Header dissapeared

Site URL: https://optios.squarespace.com/home

Hi there, 

Would anyone be able to tell me why the header on this website has dissapeared? It's about this website: 

https://optios.squarespace.com/home

We use both plug ins like Squarekicker as WeGlot and have some custom code in it, everything worked fine untill we got a remark the header was invisble on pages it should be visible (on others the header has been coded out). 

Would appreciate all feedback! 

Thanks very much! 

Without knowing which pages the header should and should not be appearing on, on the page cited the following code, apparently in SquareKicker, appears to be causing the issue.

            #siteWrapper > header {
              display: none !important;
            }

Let us know how it goes.