You are RIGHT!!!
This problem really came from node version I installed in my laptop. To make "npm link" without sudo I was using nvm to install NodeJS and I forgot to select version 12.17.0.
@RazorAxis the only thing I can think of is that some CSS style aren't being recognized by Firefox and IE for whatever theme you're using. I wouldn't expect this to happen though, since we're using bootstrap.
congrats!
