.fade {
  opacity: 0;
  -webkit-transition: opacity 0.15s linear;
     -moz-transition: opacity 0.15s linear;
      -ms-transition: opacity 0.15s linear;
       -o-transition: opacity 0.15s linear;
          transition: opacity 0.15s linear;
}

.fade.in {
  opacity: 1;
}