#back-to-top.show-btt {
bottom: 0;
opacity: 1;
transition: all .5s ease;
}
#back-to-top {
height: 50px;
width: 50px;
position: fixed;
right: 0;
z-index: 99;
border-radius: 50%;
box-shadow: 0px 0px 5px #ccc;
margin: 17px;
background: white;
bottom: -150px;
opacity: 0;
transition: all .5s ease;
}
