Issue with Improve Compatibility with Browser Fallbacks

Tell us what’s happening:
So, I have issue with this code. I think there is a bug, otherwise I believe I have done it right.

Your code so far

  :root {
    --red-color: red;
  .red-box {
    background: var(--red-cor, red);
    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/73.0.3683.103 Safari/537.36.

Link to the challenge:

Ok, I figured it out.

the code below will be added that is all
background: red;

You need to have a fallback value in case css variable doesn’t work.

On the empty line declare background with color red.