I've already tried to fix the problem by following this thread: https://stackoverflow.com/questions/17907833/content-url-does-not-display-image-on-firefox-browser#=
But the "width" CSS code won't work properly, no idea why. This is my code which works great on google chrome:
@media screen and (max-width: 991px) {
  .why35 {
    content:url('image.png');
    width:178px;
    display: inline-block;
    margin-left: auto;
    margin-right: auto;
    margin-bottom:-7px;
  }
}
I've been trying to fix it for quite some time now but it just wont work, no clue why...
Any help? I would really appreciate it.
Thank you!