Merhabalar.

Elementordan bir tema aldım kendimi geliştirmek için, header kısmında menüler var.

HTML Kodu bu:
   <!-- Start header -->
        <header id="header">
            <div class="wpo-site-header wpo-header-style-4">
                <nav class="navigation navbar navbar-expand-lg navbar-light">
                    <div class="container-fluid">
                        <div class="row align-items-center">
                            <div class="col-lg-3 col-md-3 col-3 d-lg-none dl-block">
                                <div class="mobail-menu">
                                    <button type="button" class="navbar-toggler open-btn">
                                        <span class="sr-only">Toggle navigation</span>
                                        <span class="icon-bar first-angle"></span>
                                        <span class="icon-bar middle-angle"></span>
                                        <span class="icon-bar last-angle"></span>
                                    </button>
                                </div>
                            </div>
                            <div class="col-lg-2 col-md-6 col-6">
                                <div class="navbar-header">
                                    <a class="navbar-brand logo" href="index.html"><img src="assets/images/logo2.svg"
                                            alt=""></a>
                                </div>
                            </div>
                            <div class="col-lg-9 col-md-2 col-1">
                                <div id="navbar" class="collapse navbar-collapse navigation-holder">
                                    <button class="menu-close"><i class="ti-close"></i></button>
                                    <ul class="nav navbar-nav mb-2 mb-lg-0">
                                        <li class="menu-item-has-children">
                                            <a href="#">Home</a>
                                            <ul class="sub-menu">
                                                <li><a href="index.html">Home Style 1</a></li>
                                                <li><a href="index-2.html">Home Style 2</a></li>
                                                <li><a href="index-3.html">Home Style 3</a></li>
                                                <li><a href="index-4.html">Home Style 4</a></li>
                                                <li><a href="index-5.html">Home Style 5</a></li>
                                            </ul>
                                        </li>
                                        <li><a class="active" href="about.html">About</a></li>
                                        <li class="menu-item-has-children">
                                            <a href="service.html">Service</a>
                                            <ul class="sub-menu">
                                                <li><a  href="service.html">Service</a></li>
                                                <li><a href="service-single.html">Service Single</a></li>
                                            </ul>
                                        </li>
                                        <li class="menu-item-has-children">
                                            <a href="project.html">Project</a>
                                            <ul class="sub-menu">
                                                <li><a href="project.html">Project</a></li>
                                                <li><a href="project-single.html">Project Single</a></li>
                                            </ul>
                                        </li>
                                        <li class="menu-item-has-children">
                                            <a href="blog.html">Blog</a>
                                            <ul class="sub-menu">
                                                <li><a href="blog.html">Blog right sidebar</a></li>
                                                <li><a href="blog-left-sidebar.html">Blog left sidebar</a></li>
                                                <li><a href="blog-fullwidth.html">Blog fullwidth</a></li>
                                                <li class="menu-item-has-children">
                                                    <a href="#">Blog details</a>
                                                    <ul class="sub-menu">
                                                        <li><a href="blog-single.html">Blog details right
                                                                sidebar</a>
                                                        </li>
                                                        <li><a href="blog-single-left-sidebar.html">Blog details
                                                                left
                                                                sidebar</a></li>
                                                        <li><a href="blog-single-fullwidth.html">Blog details
                                                                fullwidth</a></li>
                                                    </ul>
                                                </li>
                                            </ul>
                                        </li>
                                        <li class="menu-item-has-children">
                                            <a href="#">Pages</a>
                                            <ul class="sub-menu">
                                                <li><a href="shop.html">Shop</a></li>
                                                <li><a href="shop-single.html">Shop Single</a></li>
                                                <li><a href="cart.html">Cart</a></li>
                                                <li><a href="wishlist.html">Wishlist</a></li>
                                                <li><a href="checkout.html">Checkout</a></li>
                                                <li><a href="pricing.html">Pricing</a></li>
                                                <li><a href="team-single.html">Team Single</a></li>
                                                <li><a href="404.html">404 Error</a></li>
                                            </ul>
                                        </li>
                                        <li><a href="contact.html">Contact</a></li>
                                    </ul>

                                </div><!-- end of nav-collapse -->
                            </div>
                            <div class="col-lg-1 col-md-1 col-2">
                                <div class="header-right">
                                    <div class="header-right-menu-wrapper">
                                        <div class="header-right-menu">
                                            <div class="right-menu-toggle-btn">
                                                <span></span>
                                                <span></span>
                                                <span></span>
                                            </div>
                                            <div class="header-right-menu-wrap">
                                                <button class="right-menu-close"><i class="ti-close"></i></button>
                                                <div class="logo"><img src="assets/images/logo2.svg" alt=""></div>
                                                <div class="header-right-sec">
                                                    <div class="project-widget widget">
                                                        <h3>Our Latest Projects</h3>
                                                        <ul>
                                                            <li><a href="project-single.html"><img
                                                                        src="assets/images/projects/1.jpg" alt=""></a></li>
                                                            <li><a href="project-single.html"><img
                                                                        src="assets/images/projects/2.jpg" alt=""></a></li>
                                                            <li><a href="project-single.html"><img
                                                                        src="assets/images/projects/3.jpg" alt=""></a></li>
                                                            <li><a href="project-single.html"><img
                                                                        src="assets/images/projects/4.jpg" alt=""></a></li>
                                                            <li><a href="project-single.html"><img
                                                                        src="assets/images/projects/6.jpg" alt=""></a></li>
                                                            <li><a href="project-single.html"><img
                                                                        src="assets/images/projects/7.jpg" alt=""></a></li>
                                                        </ul>
                                                    </div>
                                                    <div class="widget wpo-contact-widget">
                                                        <div class="widget-title">
                                                            <h3>Contact Us</h3>
                                                        </div>
                                                        <div class="contact-ft">
                                                            <ul>
                                                                <li><i class="fi flaticon-location"></i>68D, Belsion Town
                                                                    2365 <br> Fna city, LH 3656, USA</li>
                                                                <li><i class="fi flaticon-telephone"></i>+ 8 (123) 123 456
                                                                    789 <br>
                                                                    + 8 (123) 123 456 789</li>
                                                                <li><i class="fi flaticon-email"></i>arkio@gmail.com</li>
                                                            </ul>
                                                        </div>
                                                    </div>
                                                    <div class="widget newsletter-widget">
                                                        <div class="widget-title">
                                                            <h3>Newsletter</h3>
                                                        </div>
                                                        <form>
                                                            <div class="input-1">
                                                                <input type="email" class="form-control"
                                                                    placeholder="Email Address *" required="">
                                                                <div class="submit clearfix">
                                                                    <button type="submit"><i class="ti-email"></i></button>
                                                                </div>
                                                            </div>
                                                        </form>
                                                    </div>
                                                </div>
                                            </div>
                                        </div>
                                    </div>
                                </div>
                            </div>
                        </div>
                    </div><!-- end of container -->
                </nav>
            </div>
        </header>
Kod temelde arka plan menüde siyah bir çerçeve içinde yayınlanıyor, yönetim panelinden veri alan header bu ;

 <!-- Header Start -->
<header id="header">
    <div class="wpo-site-header header-style-1">
        <nav class="navigation navbar navbar-expand-lg navbar-light">
            <div class="container-fluid">
                <div class="row align-items-center">
                    <div class="col-lg-3 col-md-3 col-3 d-lg-none dl-block">
                        <div class="mobail-menu">
                            <button type="button" class="navbar-toggler open-btn">
                                <span class="sr-only">Toggle navigation</span>
                                <span class="icon-bar first-angle"></span>
                                <span class="icon-bar middle-angle"></span>
                                <span class="icon-bar last-angle"></span>
                            </button>
                        </div>
                    </div>
                    <div class="col-lg-2 col-md-6 col-6">
                        <div class="navbar-header">
                            <a class="navbar-brand logo" href="index.html">
                                <img src="assets/images/logo.svg" alt="">
                            </a>
                        </div>
                    </div>
                    <div class="col-lg-8 col-md-1 col-1">
                        <div id="navbar" class="collapse navbar-collapse navigation-holder">
                            <button class="menu-close"><i class="ti-close"></i></button>
                            <?php echo renderMenu($menuItems); ?>
                        </div>
                    </div>
                    <div class="col-lg-2 col-md-2 col-2">
                        <div class="header-right">
                            <div class="header-search-form-wrapper">
                                <div class="cart-search-contact">
                                    <button class="search-toggle-btn">
                                        <i class="fi flaticon-search"></i>
                                    </button>
                                    <div class="header-search-form">
                                        <form>
                                            <div>
                                                <input type="text" class="form-control" placeholder="Arama...">
                                                <button type="submit"><i class="fi flaticon-search"></i></button>
                                            </div>
                                        </form>
                                    </div>
                                </div>
                            </div>
                            <?php if(isset($_SESSION['cart']) && count($_SESSION['cart']) > 0): ?>
                            <div class="mini-cart">
                                <button class="cart-toggle-btn">
                                    <i class="fi flaticon-shopping-cart"></i>
                                    <span class="cart-count"><?php echo count($_SESSION['cart']); ?></span>
                                </button>
                                <div class="mini-cart-content">
                                    <button class="mini-cart-close"><i class="ti-close"></i></button>
                                    <div class="mini-cart-items">
                                        <?php foreach($_SESSION['cart'] as $cartItem): ?>
                                        <div class="mini-cart-item clearfix">
                                            <div class="mini-cart-item-image">
                                                <a href="<?php echo $cartItem['url']; ?>">
                                                    <img src="<?php echo $cartItem['image']; ?>" alt="<?php echo $cartItem['name']; ?>">
                                                </a>
                                            </div>
                                            <div class="mini-cart-item-des">
                                                <a href="<?php echo $cartItem['url']; ?>"><?php echo $cartItem['name']; ?></a>
                                                <span class="mini-cart-item-price"><?php echo $cartItem['price']; ?> x <?php echo $cartItem['quantity']; ?></span>
                                                <span class="mini-cart-item-quantity">
                                                    <a href="#" class="remove-item" data-id="<?php echo $cartItem['id']; ?>">
                                                        <i class="ti-close"></i>
                                                    </a>
                                                </span>
                                            </div>
                                        </div>
                                        <?php endforeach; ?>
                                    </div>
                                    <div class="mini-cart-action clearfix">
                                        <span class="mini-checkout-price">Toplam:
                                            <span><?php echo number_format($cartTotal, 2); ?> TL</span>
                                        </span>
                                        <div class="mini-btn">
                                            <a href="checkout.php" class="view-cart-btn s1">Ödeme</a>
                                            <a href="cart.php" class="view-cart-btn">Sepet</a>
                                        </div>
                                    </div>
                                </div>
                            </div>
                            <?php endif; ?>
                        </div>
                    </div>
                </div>
            </div>
        </nav>
    </div>
</header>
Header'e arka planı siyah olacak şekilde oturtamadım, nerede hata yapıyorum acaba?

Teşekkürler.