/*网页置顶begin*/
#back-to-top {
  position: fixed;
  right: 10px;
  bottom: 10px;
  z-index: 997;
  width: 40px;
  height: 40px;
  line-height:40px;
  display: block;
  background: rgba(0, 0, 0, 0.75);
  font-size: 16px;
  text-align: center;
  border-radius: 3px;
  cursor: pointer;
  transition: background 0.25s linear;
}
#back-to-top:hover {
  text-decoration: none;
  background-color: #d0d0d0;
}
#back-to-top i {
  color: #fff;margin-top:10px;
}
/*网页置顶end*/