I have set up a js fiddle which demonstrates how axis labels can be rotated, based on an issue raised on github. It works fine in the js fiddle example below, but when I try this on my site the labels are not visible.
http://jsfiddle.net/Lnhpwn8x/22/
html {
  box-sizing: border-box;
  font-family: Roboto, sans-serif;
}
*, *:before, *:after {
  box-sizing: inherit;
}
.ct-label.ct-label.ct-horizontal {
  position: fixed;
  justify-content: flex-end;
  text-align: right;
  transform-origin: 100% 0;
  transform: translate(-100%) rotate(-45deg);
}
If I resize the screen to make it smaller the labels appear, so I think the issue is to do with the size of chart and that it is taking up 100% of the width
 
    