index.html

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>RGB Slider</title>
    <link rel="stylesheet" href="style.css">
</head>
<body>
      
      <fieldset>
        <label for="r">R</label>
        <input type="range" min="0" max="255" id="r" step="1" value="0">
      </fieldset>  
      
      <fieldset>
        <label for="g">G</label>
        <input type="range" min="0" max="255" id="g" step="1" value="0">
      </fieldset>
      
      <fieldset>
        <label for="b">B</label>
        <input type="range" min="0" max="255" id="b" step="1" value="0">
      </fieldset>  
      
      <output id="hex">RGB (0,0,0)</output>
    <script src="script.js"></script>
</body>
</html>