Improve Compatibility with Browser Fallbacks - don't understand

Tell us what’s happening:

Your code so far

  :root {
    --red-color: red;
  .red-box {
    background: var(--red-color);
    height: 200px;
<div class="red-box"></div>

Your browser information:

User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/70.0.3538.77 Safari/537.36.

Link to the challenge:

Some browsers won’t understand this css, so you can implement a fallback which the dumb browsers will understand.

So add a red background with normal/standard css and browsers that can’t read css variables will use the normal/standard syntax