#back-to-top {
    position: fixed;
    z-index: 999;
    width: 35px;
    height: 35px;
    text-align: center;
    color: #000;
    cursor: pointer;
    background: #fff;
    line-height: 35px;
    text-decoration: none;
    font-size: 1.4em;
    border: 2px solid #000;
    border-radius: 50%;
}

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

#back-to-top.TopRight {
  top: 40px;
  right: 40px;
}

#back-to-top.CenterRight {
  top: 50%;
  right: 40px;
  margin-top: -27px;
}

#back-to-top.BottomRight {
  bottom: 55px;
  right: 10px;
}

#back-to-top.TopLeft {
  top: 40px;
  left: 40px;
}

#back-to-top.CenterLeft {
  top: 50%;
  left: 40px;
  margin-top: -27px;
}

#back-to-top.BottomLeft {
  bottom: 40px;
  left: 40px;
}

/*手機版自訂css開始-------------------------------------------------------------------------*/
@media (max-width: 700px) {

#back-to-top.BottomRight {
  bottom: 253px;
}

}