title: Safari + CSS: using "calc" with "vh" does not work
body: <p>I'm encountering a very niche issue CSS issue on Safari.</p>
  
  <p>I have the following CSS rule:</p>
  
  <pre class="lang-css prettyprint-override"><code>min-height: calc(100vh - 115.5px - 25px*2);
  </code></pre>
  
  <p>This works on Chrome, but Safari doesn't seem to like the combination of <code>calc</code> and <code>vh</code>. (It works if I replace <code>vh</code> with <code>%</code>, for example--but I do need to calculate based on <code>vh</code> or some appropriate alternative.)</p>
  
  <p>Is there some way around this to make this work?  Alternatively, is there another way to refer to <code>vh</code> that is <code>calc</code>-friendly on Safari?</p>