How can I hide an element using css for mobile users? I am using gamipress with wpforo but I noticed the achievements and points push down the content head on the right side in threaded mode so there is a big empty space above the username. I want to hide the achievements and thumbnail of gamipress points on mobile phones. I tried adding this to the style:

@media only screen and (max-width: 600px) {
 .gamipress-wpforo-points-thumbnail {
display:none!important;
}
}

but it still shows up thumbnail image on mobile phones.