Hello, please share the URL and I will take a look at it. It is likely that you have a negative top margin (for example, -100px) on desktop and/or tablet that is being carried over to the mobile view. Check the section margin settings, then the column and then the individual elements.
Ok, I understand the issue now, I thought you meant it was cropping the top of the header. Try this - click on the headline, go to mobile view and set the font size using VW (view width) instead of PX. You will need to play around with the value, but this will let your set the font size based on the viewport width of the mobile device.