Improve Compatibility with Browser Fallbacks wont work

HTML-CSS
1

Tell us what’s happening:
having trouble completing this code as far as i can tell everything is done as it should be it just wont accept the answer

Your code so far


<style>
  :root {
    --red-color: red;
  }
  .red-box {
    
    background: var(--red-color, red);
    height: 200px;
    width:200px;
  }
</style>
<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/71.0.3578.98 Safari/537.36.

2

The way you did it is a fallback in case the variable doesn’t have a valid value
You need a fallback in case the browser doesn’t read variables, so you need to add an other rule, read again the challenge description