Improve Compatibility with Browser Fallbacks 3

Tell us what’s happening:
Task To DO:
It looks like a variable is being used to set the background color of the .red-box class. Let’s improve our browser compatibility by adding another background declaration right before the existing declaration and set its value to red.
What I did:
I did insert fallback inline, just like the previous lesson asked to do, as you see below, didn’t work. I need to declare/add another seperate “background: red;” for this to work. I guess the lesson right before this, make this confusing.
Here is a snapshot from the lesson:
Lesson title: “Basic CSS: Attach a Fallback value to a CSS Variable”
Here’s how you do it:

background: var(–penguin-skin, black);

Your code so far

  :root {
    --red-color: red;
  .red-box {
    background: var( --red-color, red);
    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/70.0.3538.102 Safari/537.36.

Link to the challenge:

I have issue with this code too.
I did same and it doesn’t pass to next challenge!?

it did not work!! what is the problem ??

I find the problem
.red-box {
background: red;
background: var(–red-color);
height: 200px;