I finally got my vertical table data working. It works in the latest Chrome, Edge and Explorer but Prince seems to struggle with the transformation to PDF.

 
<td rowspan="3" valign="top" align="center" style="transform: rotate(-90deg); vertical-align: middle;" colspan="1">
  <div class="table-rotated-container">
    Sections to be examined
   <div class="sts-p">and/or extent of coverage</div>
  </div>
</td> 

 
div.table-rotated-container { 
  -ms-writing-mode: tb-rl;
  -webkit-writing-mode: vertical-rl;
  display: table; 
  border-spacing: 0;
  writing-mode: vertical-rl;
  transform: rotate(-90deg);
  padding-bottom: 3pt;
}

What part of this does Prince exactly have a problem? It seems to me that Prince forces the "white-space: nowrap;" effect on the transformation.

I've attached an image of the situation and .html file with the problematic vertical table data.

1. situation.png‎ 18.3 kB
2. vertical_td.html‎ 8.7 kB

Edited 5 Feb 2019 by rainhallikas

Got it. Prince html.css had a conflicting line:

 *:not(table)[align="center"] { text-align: center; } 

Overrode the text-align property with '-webkit-center !important'