False white space above header

Hi there,

I just worked on an entry and saved it but didn’t publish and when I loaded the website I realised a wrong big white space above my header. I don’t know for how long it’s been there, but maybe you have seen this problem before and know how to fix it or start looking for the problem: https://www.nadjakuschel.com/blog/

Would it help updating WordPress?

Thanks in advance,
Nadja