Few UX suggestions:

1. People might be more inclined to be interested in applying to be a co-founder if they can actually read the information on the founder/company before applying. However, currently there is a login barrier to seeing that information which may cause some people to decide it isn't worth it and leave the website without looking.

2. Add an easy way to close the login modal. Currently the only way I found was th e back button and that isn't a good solution for the reason in #3

3. Don't hijack the user's history and take control over the back button, it is very user un-friendly