Desktop-first approach with Webpack | SASS | Babel

So, this one was a mixture of feelings, rsrs.

I would LOVE feedback on my media queries because I took a desktop-first approach and I REALLY struggled with the mobile layout. For this project I tried to go the extra mile in some aspects, and I used Webpack, SASS and Babel (as transpiler). It was really fun do set all these things up and have a more realistic idea of a real project, feedback on this setup would also be highly appreciated.

The active states didn`t specify anything to be done in case of a valid email, so I threw an alert message and changed the border of the form, just to provide a visual confirmation that the email was accepted.

Is there any other way I could`ve set the height? I had to hard code it because there was an annoying gap below the whole screen...

Anyway, thanks for taking the time to check my solution!