Hello Jan,
Those classes might already have media queries on them, I suggest you test it on mobiles/browser with mobile view.
I'm not that familiar with Atlas UI, but in older Mx versions we use a .visible-xs class which is tied in with bootstrap and has media queries so it will make it visible only on mobile sized screens/browsers.
Hope this helps.
Oh wauw you're right! It's right there on mobile haha!
Then I need to figure out how to let it appear on desktop as well!