Stuck at Compatibility with Browser Fallbacks

HTML-CSS
1

Tell us what’s happening:

Your code so far


<style>
  :root {
    --red-color: red;
  }
  
.red-box { 
    background-color: red;
  }
  .red-box {
  background: var(--red-color,);
    height: 200px;
    width:200px;
  }
</style>
<div background-color="red" class="red-box"></div>

Your browser information:

User Agent is: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/12.0.2 Safari/605.1.15.

Link to the challenge:
https://learn.freecodecamp.org/responsive-web-design/basic-css/improve-compatibility-with-browser-fallbacks

2

try this:

:root {
–red-color: red;
}
.red-box {
background:red;
background: var(–red-color);
height: 200px;
width:200px;
}

3

only add" background:red;" before “background: var(–red-color);” and after “.red-box {”.