If you're the first Anonymous Monk then I have also clicked your link and didn't find that it addressed what the OP was looking for. It's a helpful link and all but it won't fix the problem.
I went to the site and looked at the source code. The problem here is JustAnswer has missed some logic in their JavaScript code. When you turn off JavaScript it shows the SIGN UP form and never lets you see the sign IN form.
Best thing to do is let them know they have a bug in their code and wait for them to fix it. Then your code should work fine.