title: How to give opacity to a color with hex value in css?
body: <p>In hsl value, we can give opacity as</p>
  <pre><code>background: hsla(213, 34%, 12%, .5);
  </code></pre>
  <p>and in rgb as</p>
  <pre><code>background: rgba(134, 231, 54, .5);
  </code></pre>
  <p>I wonder how we can give opacity to hex value?</p>