#backtotop {
  background: transparent;
  width: 72px;
  height: 72px;
  opacity: 0.4;
  right: 20px;
  bottom: 20px;
  position: fixed;
  cursor: pointer;
  border: 2px solid transparent;
}

#backtotop:hover {
  opacity: 1;
}

.btt-background {
  position: relative;
  display: block;
  width: 100%;
  height: 100%;
  background: #3094B5;
}

#backtotop:before{
  position: absolute;
  display: block;
  content: "";
  width: 34px;
  height: 25px;
  z-index: 2;
  background: url("../images/layout/arrow_BtT.png") no-repeat;
  top: 50%;
  left: 50%;
  transform: translate(-50%, -50%);
  -ms-transform: translate(-50%, -50%);
  -webkit-transform: translate(-50%, -50%);
  -o-transform: translate(-50%, -50%);
}

@media only screen and (max-width: 719px) {
  #backtotop {
    width: 43px;
    height: 43px;
  }

  #backtotop:before{
    width: 21px;
    height: 15px;
    background: url("../images/layout/arrow_BtT_small.png") no-repeat;
  }
}