title: Convert opacity with var scss sass
body: <p>I have some property like this</p>
  <pre class="lang-css prettyprint-override"><code>::root {
    --light-grey: #EFEFEF;
  }
  
  .content-wrapper {
    background-color: rgba(#EFEFEF, .4);
    border-radius: 8px;
    padding: 25px 33px;
  }
  </code></pre>
  <p>But when I try</p>
  <pre class="lang-css prettyprint-override"><code>.content-wrapper {
    background-color: rgba(var(--light-grey), .4);
    border-radius: 8px;
    padding: 25px 33px;
  }
  </code></pre>
  <p>This does not works, grey background color is not shown?</p>