What potential issues can arise when using multiple DOCTYPE, head, body, and CSS definitions in PHP code?

Potential issues that can arise when using multiple DOCTYPE, head, body, and CSS definitions in PHP code include conflicting declarations, rendering issues, and invalid HTML structure. To solve this problem, it is important to ensure that these elements are properly structured and organized within the PHP code to avoid conflicts and maintain a consistent layout. 

<!DOCTYPE html>
<html>
<head>
    <title>Page Title</title>
    <link rel="stylesheet" type="text/css" href="styles.css">
</head>
<body>
    <div class="container">
        <?php
        // PHP code here
        ?>
    </div>
</body>
</html>

Keywords

DOCTYPE head body CSS conflicts

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