Improve Compatibility with Browser Fallbacks - I need help

Tell us what’s happening:

Can someone explain this?

Your code so far

  :root {
    --red-color: red;
  .red-box {
    background: var(red)!important; 
    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/72.0.3626.121 Safari/537.36.

Link to the challenge:

Well, that wouldn’t work. But, remember how you would set a background to the color red before learning about variables? That is what a browser that is not able to read variables would use

I’m still not sure…

Do you mean like using CSS selectors?

I mean the value you would but after the column. Just make the background red without using the variables, like you would have done before learning variables exist in css