50px wide stripe above the header

Hello!

I changed the background color to white, and when the website loads in mobile view, a 50px height white stripe is generated above the header. I only experience it in mobile view or when I resize the browser on my PC.

I checked the css of it and I get this:

element.style {
padding-top: 50px;
}

I tried to change it to 0px within the Wordpress css editor but nothing happens.

I'm a total beginner.

What can I do to get rid of that white stripe?

Please check some pages on the website.

Thanks you.

Regards, Imre