.back-to-top {
    background-color: #8A2BE2;
    color: #FFFFFF;
    opacity: 0;
    transition: opacity .6s ease-in-out;
    z-index: 999;
    position: fixed;
    right: 20px;
    bottom: 20px;
    width: 150px;
    height: 50px;
    box-sizing: border-box;
    border-radius: 10%;
     border-radius: 10px;
     border: 4px double #cccccc;
        -webkit-transition: all 0.5s;
        -moz-transition: all 0.5s;
        -o-transition: all 0.5s;
        transition: all 0.5s;
        cursor: pointer;
        margin: 5px;
  }

  a.back-to-top {
    font-weight: 1000;
    letter-spacing: 2px;
    font-size: 14px;
    text-transform: uppercase;
    text-align: center;
    line-height: 1.6;
    padding-left: 2px;
    padding-top: 14px;
  }

  .back-to-top:hover, .back-to-top:focus, .back-to-top:visited {
    color: #FFFFFF;
  }

  .back-to-top.show {
    opacity: 1;
  }