/* Back to top button
**************************/
#tt_box {
  position: fixed;
  left: 0;
  right: 0;
  bottom: 0;
  z-index: 0;
}

#tt_wrap {
  position: relative;
  width: 990px;
  margin: 0 auto;
}

#tt_button {
  cursor: pointer;
  position: absolute;
  right: calc((100% - 1080px) / 0.82);
  bottom: 95px;
  width: 30px;
  height: 30px;
  line-height: 26px;
  border-radius: 50%;
  background: #777;
  background-color: rgba(0,0,0,0.4);
  color: #fff;
  font-size: 24px;
  text-align: center;
  z-index: 99999;
}