.centered-btns_nav {
  z-index: 3;
  position: absolute;
  /*-webkit-tap-highlight-color: rgba(0,0,0,0);*/
  top: 50%;
  left: 0;
  /*opacity: 0.7;*/
  text-indent: -9999px;
  overflow: hidden;
  text-decoration: none;
  height: 42px;
  width: 50px;
  /*background: transparent url("themes.gif") no-repeat left top;*/
  
  margin-top: -45px;
  }

.centered-btns_nav:active {
  /*opacity: 1.0;*/
  }

.centered-btns_nav.next {
  left: auto;
  /*background-position: right top;*/
  right: 0;
  
  background: transparent url("../img/next-arrow.png") no-repeat left top;
  
  
  }
.centered-btns_nav.prev {

  background: transparent url("../img/previous-arrow.png") no-repeat left top;
  
  
  }