.container {
  position: relative;
   display: inline-block;
  padding: 10rem;
  border: 1px solid;
}

.container:before {
  position: absolute;
  right: 0;
  bottom: 0;
  content: "some sss fasdf asdf";
  transform: rotate(-90deg) translate(100%, 0);
  transform-origin: right bottom;
}