Footer columns on mobile

Hello,

I don’t really know much about CSS and I’ve tried a lot a different things to solve my problem (including looking at existing posts), but nothing seems to work.

Here’s the problem: on my website, my footer has 3 columns. The first one is aligned left, the second one is aligned center and the last one is aligned right. It looks good on a computer, but not on a mobile device. On a phone, I would like the three columns to be centered. Does anyone know how to do that?

Thanks in advance!

The page I need help with: [log in to see the link]