Compatibility Improvement with Browser Fallbacks

Tell us what’s happening:

Your code so far

  :root {
    --fb: yellow;
    --red-color: red,  yellow;
  .red-box {
    background: var(--red-color, --fb);
    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/75.0.3770.100 Safari/537.36.

Link to the challenge:

There is an empty line for the .red-box selector, you need to add something there. Even if you do that right, if you change anything else you will not be able to pass tests

A browser fallback is needed when the browser doesn’t support variables, and what the browser needs is a declaration that doesn’t use variables - how would you set the background if you didn’t know about variables?