Add space between header and top of page

Hello everyone,

I’m really new to wordpress and started using it because it was recommended to me. Now i’m using the Mantra theme and it’s given me everything i needed so far but when it comes to outside of the theme settings editing i can’t get much done. I’ve tried creating child theme but it’s just too technical t.b.h.

I am trying to add empty space between the top of the page and the header, so i would like my page to be pushed down a bit (~ 100px). I tried searching for an answer but i can’t find anyhting. I tried editing the CSS but nothing changes. Now i did find out through google chrome that the area above the header is the div masthead. But i can’t find it anywhere in any of the CSS docs of the theme.

My website is: http://www.stapsteen-begeleiding.nl.

Hope someone can help me.