IN CSS My linear-gradient (in .red class selector) doesn't work(even when I use to the type of coloring method), why is that

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Your code so far

<!-- file: index.html -->
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="utf-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Colored Markers</title>
    <link rel="stylesheet" href="styles.css">
  </head>
  <body>
    <h1>CSS Color Markers</h1>
    <div class="container">
      <div class="marker red">
      </div>
      <div class="marker green">
      </div>
      <div class="marker blue">
      </div>
    </div>
  </body>
</html>
/* file: styles.css */
h1 {
  text-align: center;
}

.container {
  background-color: rgb(255, 255, 255);
  padding: 10px 0;
}

.marker {
  width: 200px;
  height: 25px;
  margin: 10px auto;
}

.red {
  background:linear-gradient(90deg,rgb(255,0,0),#00FF00);
   }

.green {
  background-color: #007F00;
}

.blue {
  background-color: hsl(240, 100%, 50%);
}

type or paste code here

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User Agent is: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/106.0.0.0 Safari/537.36

Challenge: Learn CSS Colors by Building a Set of Colored Markers - Step 50

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