XF 2.1 struggling to hide from mobile

[Martyn]

I'm trying to make a "snowy" thing above the avatars not show on mobile (see below)


with the code

.userExtra--expand:before {
      content: " ";
      background: transparent url('https://img.URL/XLpgCd6C.png') no-repeat;
      width:155px;
      height:24px;
      display:block;
      position: absolute;
      top:-16px;
      right:-9px;
      z-index:1;
  }

but when I put it inside of

@media (max-width:@maxResponsiveWideWide){

}

it just doesn't display?

I must be doing something wrong >.<