_navbar.cshtml

<!-- Navbar Start -->
@{
    var userID_nav = Convert.ToString(Session["userID"]);

}

<nav class="navbar navbar-expand-lg bg-white navbar-light shadow sticky-top p-0">
    <a href="~/index.cshtml" class="navbar-brand d-flex align-items-center px-4 px-lg-5">
        <h2 class="m-0 text-primary"><i class="fa fa-book me-3"></i>SkillShare</h2>
    </a>
    <button type="button" class="navbar-toggler me-4" data-bs-toggle="collapse" data-bs-target="#navbarCollapse">
        <span class="navbar-toggler-icon"></span>
    </button>
    <div class="collapse navbar-collapse" id="navbarCollapse">
        <div class="navbar-nav ms-auto p-4 p-lg-0">
            <a href="~/index.cshtml" class="nav-item nav-link">Home</a>

            <a href="~/profile.cshtml" class="nav-item nav-link">Profile</a>

            <a href="~/courses.cshtml" class="nav-item nav-link">Courses</a>
            <!-- Only show "Your Lectures" link when logged in -->

            <div class="nav-item dropdown">
                <a href="#" class="nav-link dropdown-toggle" data-bs-toggle="dropdown">Pages</a>
                <div class="dropdown-menu fade-down m-0">
                    <a href="~/instructors.cshtml" class="dropdown-item">Instructors</a>
                    <a href="~/discussion.cshtml" class="dropdown-item">Discussion</a>
                    <a href="~/404.cshtml" class="dropdown-item">404 Page</a>
                </div>
            </div>
            <a href="~/contact.cshtml" class="nav-item nav-link">Contact</a>
            <!-- Show log out button only when logged in -->
            @if (!string.IsNullOrEmpty(userID_nav))
            {
                <a href="~/login.cshtml" class="btn btn-primary py-4 px-lg-5 d-none d-lg-block">Log Out<i class="fa fa-arrow-right ms-3"></i></a>
            }
            <!-- Show join button only when logged out -->
            @if (string.IsNullOrEmpty(userID_nav))
            {
                <a href="~/login.cshtml" class="btn btn-primary py-4 px-lg-5 d-none d-lg-block">Join Now<i class="fa fa-arrow-right ms-3"></i></a>
            }
        </div>
    </div>
</nav>
<!-- Navbar End -->