<section id="cover">
        <nav class="navbar navbar-expand-lg navbar-dark navbar-custom fixed-top">
            <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarNavDropdown" aria-controls="navbarNavDropdown" aria-expanded="false" aria-label="Toggle navigation">
                <span class="navbar-toggler-icon"></span>
            </button>
            <div class="collapse navbar-collapse" id="navbarNavDropdown">
                <ul class="navbar-nav mx-auto">
                    <li class="nav-item">
                        <a class="nav-link" href="#">Anasayfa</a>
                    </li>
                    <li class="nav-item dropdown">
                        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                            Kurumsal
                        </a>
                        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                            <a class="dropdown-item" href="#">Hakkımızda</a>
                            <a class="dropdown-item" href="#">Sertifikalarımız</a>
                            <a class="dropdown-item" href="#">Ekibimiz</a>
                        </div>
                    </li>
                    <li class="nav-item dropdown">
                        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                            Hizmetler
                        </a>
                        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                            <a class="dropdown-item" href="#">Chip Tuning Ekonomik</a>
                            <a class="dropdown-item" href="#">Chip Tuning Performans</a>
                            <a class="dropdown-item" href="#">DTC Deaktivasyonu</a>
                            <a class="dropdown-item" href="#">EGR Deaktivasyonu</a>
                            <a class="dropdown-item" href="#">DPC Deaktivasyonu</a>
                            <a class="dropdown-item" href="#">AdBlue Deaktivasyonu</a>
                            <a class="dropdown-item" href="#">Gizli Özellik</a>
                        </div>
                    </li>
                    <ul class="nav navbar-nav navbar-logo mx-auto">
                        <li class="nav-item">
                        <a class="nav-link" href="#">LOGO</a>
                        </li>
                    </ul>
                    <li class="nav-item">
                        <a class="nav-link" href="#">SSS</a>
                    </li>
                    <li class="nav-item dropdown">
                        <a class="nav-link dropdown-toggle" href="#" id="navbarDropdownMenuLink" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                            Bayilik
                        </a>
                        <div class="dropdown-menu" aria-labelledby="navbarDropdownMenuLink">
                            <a class="dropdown-item" href="#">Bayilik Başvurusu</a>
                            <a class="dropdown-item" href="#">Bayilik Şartları</a>
                            <a class="dropdown-item" href="#">Bayilerimiz</a>
                        </div>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="#">Referanslar</a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="#">İletişim</a>
                    </li>
                </ul>
            </div>
        </nav>
    </section>

html,
body,
#cover {
    height: 100%;
}

#cover {
    background: url('../spd_img/porsche.gif') no-repeat center center fixed;
    background-size: cover;
    -webkit-background-size: cover;
    -moz-background-size: cover;
    -o-background-size: cover;
}

.navbar-custom {
    padding-top: 1rem;
    padding-bottom: 1rem;
    background-color: black;
}

.fixed-top {
    position: fixed;
    top: 0;
    right: 0;
    left: 0;
    z-index: 1030;
}

a.nav-link {
    font-family: 'Montserrat', sans-serif;
    font-size: 14px;
    color: #fff !important;
    font-weight: 700;
    text-transform: uppercase;
    margin-left: 10px;
    transition: color 0.5s ease;
    -webkit-transition: color 0.5s ease;
    -moz-transition: color 0.5s ease;
    -o-transition: color 0.5s ease;
}