How I'm I going to make the background color

Tell us what’s happening:
Describe your issue in detail here.

  **Your code so far**

<style>
:root {
  --red-color: red;
}
.red-box {

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

  background: var(--red-color);
  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/97.0.4692.99 Safari/537.36 Edg/97.0.1072.69

Challenge: Improve Compatibility with Browser Fallbacks

Link to the challenge:

It looks like accidentally submitted your post before you asked a question.

What is exactly the trouble? Because you have a background color red for your class 200px x 200px. Also, look well what is inside your style tags, because one of the class/id you use is note noted on the good way and there is a form of repetition

The issue has been resolved