Edit in JSFiddle

.t-button01 {
  position: fixed;
  right: 0;
  top: 50%;
  width: 100px;
  height: 100px;
  background-color: black;
  color: white;
  text-align: center;
}

.rotate {
  /* Safari */
  -webkit-transform: rotate(-90deg);
  /* Firefox */
  -moz-transform: rotate(-90deg);
  /* IE */
  -ms-transform: rotate(-90deg);
  /* Opera */
  -o-transform: rotate(-90deg);
  /* Internet Explorer */
  filter: progid: DXImageTransform.Microsoft.BasicImage(rotation=3);
}
<span class="t-button01 rotate">Side Button</span>