Problems w Improve Compatibility w Browser Fallbacks

i’m having trouble with this lesson i can’tunderstand what i’m doing wrong

Your code so far

:root {
  --red-color: red;
.red-box {
  background: 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/87.0.4280.66 Safari/537.36.

Challenge: Improve Compatibility with Browser Fallbacks

Link to the challenge:

you are not wrong in your code, but it seems you have changed the starting code and that makes the tests fail - try resetting the code and add again the required line

thank you very much for your time, it worked