Custom 404 page is not being displayed

[aditya-adiraju]

I was going through the website and noticed when you go to a webpage that doesn't exist like maplebacon.org/foo. It's showing GitHub's default 404 error page. (Attached Below)

I looked at the source code and noticed we do have a custom page, so I guess I'll open a PR for that.

EDIT: On a custom build where I got it to work, I noticed there's no way to actually go back to the main website. So I'll add a basic version of the header (without the navbar)