Fixed by fixing the length for now.

Thanks. Makes sense, didn't test for long title, limit the heading in mobile?

I'd recommend not doing that as it makes the UX on mobile worse and has a bad influence on SEO. Instead, I usually do something like that:

    h1::first-line {font-size:2rem;}
    h1 {font-size:1.5rem;}

It will show the first line of a heading in a larger and all further lines in a smaller font size. Additionally, you could hyphenate headings.

edit: And fluid typography might be something to look into. Currently, you seem to have a single breakpoint where font size is adapted. That does not work well on larger phones.

Did not think though responsiveness a lot. Is kind of MVP. Though have made some tweaks for mobile view now.