How to do it. i don`t know

Tell us what’s happening:

Your code so far

 :root {
   --red-color: red;
 .red-box {
   backgrund: red;
   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/80.0.3987.163 Safari/537.36.

Challenge: Improve Compatibility with Browser Fallbacks

Link to the challenge:

there is a typo in your code backgrund
check on it