Hide elements only in Percy renderer

hide-flappy-elem.css

/*
This is an example of how to add special CSS that only applies in Percy's
rendering environment, for example to hide certain dynamic elements.

This is a bit of hack, we don't guarantee this will work forever in Percy
and we'll be adding a more officially-supported mechanism for this.
*/
@-moz-document domain(proxyme.percy.io) {
  #flappy-div {
    visibility: hidden !important;
  }
}