Upon inspection, it appears that there are some issues in your navigation.php code. The problem lies in the fact that you are opening the <html> and <body> tags within this file. Subsequently, in registration.php, you are including navigation.php which leads to the opening of another <body> tag, essentially merging two separate HTML documents. A better alternative to using <br> tags would be to utilize the mb-2 or similar classes from Bootstrap, as these classes serve to add margin-bottom and create space between elements.
Furthermore, in your footer.php, ensure that your scripts are placed right before the closing <body> tag to maintain proper document structure.
For the Registration page, the code is as follows:
<!DOCTYPE html>
<html lang="en">
<head>
<title>SMS</title>
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<link href="bootstrapfile/bootstrap.min.css" rel="stylesheet">
</head>
<body>
<?php
include "navigation.php"
?>
<section>
<div class="container">
<div class="row d-flex justify-content-center align-items-center h-100">
<!-- Your existing HTML content here -->
</div>
</div>
</section>
<?php include "footer.php" ?>
</body>
</html>
For Navigation.php:
<nav class="navbar navbar-expand-sm bg-info navbar-light mb-2">
<!-- Your navigation menu content here -->
</nav>
And for Footer.php:
<footer class="text-center text-lg-start bg-info text-muted">
<!-- Your footer content here -->
</footer>
Remember to paste any JavaScript tags at the end of the body tag for proper functionality.