#backtotop
  position: fixed;
  right: 50px;
  bottom: 50px;
  display: block;
  visibility: hidden;
  width: 42px;
  height: 43px;
  background: url(images/backtotop.png) no-repeat 50% 0;
  opacity: 0;
  -webkit-transition: visibility 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335), opacity 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335), -webkit-transform 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335);
  -moz-transition: visibility 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335), opacity 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335), -moz-transform 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335);
  transition: visibility 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335), opacity 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335), transform 0.6s cubic-bezier(0.6, 0.04, 0.98, 0.335);
  @media mq-mobile
    right: 12px;
    bottom: 20px;
#backtotop i {
  display: block;
  margin-top: 48px;
  height: 14px;
  background: url(images/backtotop.png) no-repeat 50% -20px;
  opacity: .5;
  -webkit-transition: -webkit-transform .2s;
  -moz-transition: -moz-transform .2s;
  transition: transform .2s;
  -webkit-transform-origin: 50% 0;
  -moz-transform-origin: 50% 0;
  transform-origin: 50% 0; }
#backtotop.show {
  visibility: visible;
  opacity: 0.50; }
#backtotop.launch {
  background-position: 50% -44px;
  opacity: 0;
  -webkit-transform: translateY(-500px);
  -moz-transform: translateY(-500px);
  -ms-transform: translateY(-500px);
  transform: translateY(-500px);
  pointer-events: none; }
#backtotop.launch i {
  background-position: 50% 100%;
  -webkit-transform: scale(1.4, 3.2);
  -moz-transform: scale(1.4, 3.2);
  transform: scale(1.4, 3.2); }