What steps can be taken to prevent content overlap or display issues in PHP scripts when integrating with external elements like banners or headers?

Content overlap or display issues in PHP scripts when integrating with external elements like banners or headers can be prevented by properly structuring the HTML output. This can be achieved by using CSS to control the layout and positioning of elements, as well as using PHP functions to conditionally include external elements based on certain criteria.

<?php
// Check if the user is logged in before displaying the banner
if (isset($_SESSION['user_id'])) {
    include 'banner.php';
}

// Include the header file
include 'header.php';

// Main content of the page
echo "<div class='content'>Lorem ipsum dolor sit amet, consectetur adipiscing elit.</div>";

// Include the footer file
include 'footer.php';
?>