<div class="app-shell" style="display: flex; min-height: 100vh;">
    <?php require __DIR__ . '/sidebar.php'; ?>
    
    <div class="app-main" style="display: flex; flex-direction: column; flex: 1; min-height: 100vh; position: relative;">
        
        <?php require __DIR__ . '/topbar.php'; ?>
        
        <main class="app-content" style="flex-grow: 1; padding: 20px;">