.btioverlay {
  position: absolute;
  display: none;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
  right: 0;
  bottom: 0;
  background-color: rgba(0,0,0,0.5);
  z-index: 2;
  cursor: pointer; }

.particleoverlay{
  position: relative;
  display: inline-block;
  /*top: 50%;*/
  left: -40%;
  /*transform: translate(-10%,-10%);*/
  /*-ms-transform: translate(-50%,-50%);  }*/
}

.centeredoverlay{
  position: relative;
  display: inline-block;
  top: 50%;
  left: 50%;
  transform: translate(-50%,-50%);
  -ms-transform: translate(-50%,-50%);  }

  .wrapper {
      display: inline-block;
      position: relative;
  }

  .hover {
      position: absolute;
      top: 0;
      left: 0;
      right: 0;
      bottom: 0;
      background-color: rgba(0, 188, 212, 0);
      transition: background-color 0.5s;
  }

  .hover:hover {
      background-color: rgba(0, 188, 212, 0.8);
      // You can tweak with other background properties too (ie: background-image)...
  }