can’t edit newsletter css in mobile view

Hello,

I struggle to edit my newsletter’s footer layout in mobile view,

Preview:
https://www.wiserockproperty.com/?mailpoet_router&endpoint=view_in_browser&action=view&data=WzEzLCJhOTFiNDdkOTA4MzgiLDAsMCwwLDFd

How can I get the 3 boxes align center for under 500px width view?
At the moment, the first box is aligned left, the second box is aligned center underneath and the third is underneath on the right.

My custom css don’t seem to be applied, even using “important”.

Thank you

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