Where are Jellyfin PHP/HTML files kept? (specifically the login page file)

I’ve wanted to modify my login page to have a “Sign Up” button linked to a plugin, though haven’t been able to find the login php/html file to edit it. Where is it located on a normal jellyfin installation?

Jellyfin is a not web a server application having php or html files. It’s an own app . Source code for jellyfin-web is located at GitHub GitHub - jellyfin/jellyfin-web: Web Client for Jellyfin

Oh. Does that mean it’s impossible to edit the page? I’m pretty new to server hosting.

There is a build-in feature to add CSS rules:

And there are also themes available like this
and this

tysm! This works perfectly for me