table, tr, td, th {
  border: 1px solid #000;
  position: relative;
  padding: 10px;
}

th span {
  transform-origin: 0 50%;
  transform: rotate(-90deg); 
  white-space: nowrap; 
  display: block;
  position: absolute;
  bottom: 0;  
  left: 50%;
}