index.html

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Text Editor app</title>
    <link rel="stylesheet" href="style.css">
    <link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/animate.css/4.1.1/animate.min.css"
        integrity="sha512-c42qTSw/wPZ3/5LBzD+Bw5f7bSF2oxou6wEb+I/lqeaKV5FDIfMvvRp772y4jcJLKuGUOpbJMdg/BTl50fJYAw=="
        crossorigin="anonymous" referrerpolicy="no-referrer" />
</head>

<body>
    <header id="main_heading">
        <center>SB Text Editor Ver 1.0.0</center>
    </header>

    <fieldset id="code_box1">
        <legend id="Heading">TYPE YOUR CODE HERE</legend>
        <textarea id="code">

<!DOCTYPE html>
<html lang="en">
<head>
<title>
    SB Text Editor
</title>
</head>
<body>

</body>
</html>
        </textarea>
    </fieldset>

    <fieldset id="code_box2">
        <legend>Output Of Your Code</legend>
        <div id="result">

        </div>
    </fieldset>

    <center>
        <button id="run_btn" onclick="run()">Run Code !</button> <button id="return_btn" onclick="back()">Return To Code
            !</button>
    </center>


    <script src="script.js"></script>
</body>

</html>