fix(public) better structure

components/structure/main.php

@@ -0,0 +1,34 @@
+<?php 
+session_start();
+
+include __DIR__ . '/../../config.php';
+
+$page = basename($_SERVER['PHP_SELF']);
+if (!isset($_SESSION['user_id']) && $page !== 'login.php' && $page !== 'register.php') {
+    header("Location: login.php");
+    exit();
+} else if (isset($_SESSION['user_id']) && ($page === 'login.php' || $page === 'register.php')) {
+    header("Location: index.php");
+    exit();
+}
+
+include 'header.php'; 
+include 'navbar.php'; 
+include __DIR__ . '/../../services/db.php'; 
+    
+?>
+
+<main class="container mt-4">
+    <?php include $content; ?>
+</main>
+
+<?php include 'footer.php'; ?>
+
+<script>
+    window.addEventListener('load', function() {
+        document.body.style.display = 'block';
+    });
+</script>
+
+</body>
+</html>