#back-to-top {
  position: fixed;
  z-index: 999;
  width: 34px;
  height: 34px;
  padding: 0;
  border: 0;
  text-align: center;
  color: transparent;
  cursor: pointer;
  line-height: 35px;
  font: inherit;
  font-size: 1.4em;
  border-radius: 0;
  transition: 0.4s;
  opacity: 0.4;
  background: url(https://nebulax.noonspace.com/w82/developer/MsgInfo/top_arrow.svg);
}
#back-to-top:hover {
  transition: 0.4s;
  opacity: 1;
}

#back-to-top:focus-visible {
  outline: 2px solid currentColor;
  outline-offset: 2px;
  opacity: 1;
}

#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: 222px;
  right: 35px;
}

#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 {
    right: 15px;
  }
}