<nav class="bottom-nav">
    <a href="index.php" class="nav-item <?php echo basename($_SERVER['PHP_SELF']) === 'index.php' ? 'active' : ''; ?>">
        <span>🏠</span>
        <small>Home</small>
    </a>
    <a href="bill.php" class="nav-item <?php echo basename($_SERVER['PHP_SELF']) === 'bill.php' ? 'active' : ''; ?>">
        <span>🧾</span>
        <small>Bill</small>
    </a>
    <a href="stock.php" class="nav-item <?php echo basename($_SERVER['PHP_SELF']) === 'stock.php' ? 'active' : ''; ?>">
        <span>📦</span>
        <small>Stock</small>
    </a>
    <a href="purchases.php" class="nav-item <?php echo basename($_SERVER['PHP_SELF']) === 'purchases.php' ? 'active' : ''; ?>">
        <span>🛒</span>
        <small>Purchases</small>
    </a>
</nav>