(Foxeed-Lite) Header coming up stretched on mobile

Hi there, been racking my brain wondering why this is happening.

Here’s my website, https://padraigstapleton.net/, and when I check on mobile, the header on the about page is coming up very stretch. It might be a theme problem because even when you see the mobile preview and tablet preview, still comes up stretched. Is there a workaround for this? Many thanks!