Random quote for log in page? Just an Idea/inquiry

So I installed the ‘Custom CSS’ app to themes. I don’t know anything about CSS or HTML code. I understand it enough that if someone has built something, I can typically edit small things to customize it but I wouldn’t even know where to begin on a project from the ground up. I’ll cut to the chase. What I’m wanting to do is make a line on the log in page that pulls a random quote from a random quote generator repository (website). (there are several out there) and displays it below the login prompt a little above the ‘slogan.’ I wouldn’t think this would take much code. Any help much appreciated. (Also not sure if this would be possible through the Custom CSS app or not. I hope I don’t sound completely ignorant to how this whole thing works.