Hex Colour Code Generator

<!doctype html>
<html>
<head>
<meta charset="UTF-8">
<title>Hex Colour Code Generator</title>
<script type="php">
    <?php function generateRandomString($length = 6) {
    $characters = '0123456789ABCDEF';
    $charactersLength = strlen($characters);
    $randomString = '';
    for ($i = 0; $i < $length; $i++) {
        $randomString .= $characters[rand(0, $charactersLength - 1)];
    }
    return $randomString;
}

    $hexCode = generateRandomString(); ?>
    </script>
<style>
    body {  background-color: #<?php echo $hexCode; ?>;
        font-family: Arial, Helvetica, sans-serif;
        font-size: 6em;
        color: #FFF;
        padding-left: 40px;
        padding-top: 20px;
    }

    p { padding: 0;
        margin: 0;}
</style>
</head>

<body>
<p>#<?php echo $hexCode ?></p>
</body>
</html>