First steps towards making the form reponsive to screensize.

I didn't finish the work since it is quite involved to get the layout just right, and I wanted to get some feedback before doing so. I propose that the subsequent parts of the form can be done in another MR.

The ideas is that you should be able to resize your browser and the form looks good no matter the size of the browser (using the bootstrap grid system at https://getbootstrap.com/docs/4.6/layout/overview/).