title: CSS `height: calc(100vh);` Vs `height: 100vh;`
body: <p>I'm working on a project where the former developer used:</p>
  
  <pre><code>.main-sidebar {
      height: calc(100vh);
  }
  </code></pre>
  
  <p>I have no way to contact him/her anymore, and I would like to understand what is the difference (if any) between the two methods.</p>
  
  <p>(Is this the right place to ask this question?)</p>