If you want to use Facebook Clone on mobile device you can check Css :

try to add some : "min-width: 300px;"

I add this line for ".join_left" and ".join_right" css class :

.join_left {

  float: left;

  width: 48%;

  min-width: 300px;

}

.join_right {

  max-width: 450px;

  float: right;

  width: 48%;

  min-width: 300px;

}

I hope this can help you while developer working on a new update !

This is a very great plugin J