title: Unexpected token 1fr in wordpress editor
body: <p>I just want to ask a simple question.
  When I try to style the HTML element in the style.css file. And after applying the style which looks like:</p>
  
  <pre><code>-ms-flex-wrap: wrap;
      flex-wrap: wrap;
      -webkit-box-pack: justify;
      -ms-flex-pack: justify;
      justify-content: space-between;
      display: grid;
      grid-gap: 20px;
      grid-template-columns: 1fr 1fr 1fr;
  </code></pre>
  
  <p>But the wordpress editor shows error: unexpected token '1fr'.
  Can you just tell me why it is showing if the CSS property is right?
  Thanks</p>