Header fixed top

    <!--Header Start-->
    <header class="z-fixed header-fixed-top">
        <nav class="navbar navbar-expand-lg navbar-light bg-body shadow-lg">
            <div class="container position-relative">
                <a class="navbar-brand" href="index.html">
                    <img src="assets/img/logo/logo.svg" alt="" class="img-fluid navbar-brand-light">
                    <img src="assets/img/logo/logo-white.svg" alt="" class="img-fluid navbar-brand-dark">
                </a>
                <div class="d-flex align-items-center navbar-no-collapse-items order-lg-last">
                    <button class="navbar-toggler order-last" type="button" data-bs-toggle="collapse"
                        data-bs-target="#mainNavbarTheme" aria-controls="mainNavbarTheme" aria-expanded="false"
                        aria-label="Toggle navigation">
                        <span class="navbar-toggler-icon">
                            <i></i>
                        </span>
                    </button>
                    <div class="nav-item me-3 me-lg-0">
                        <a href="#" class="btn btn-sm btn-primary rounded-pill">
                            Purchase
                        </a>
                    </div>
                </div>
                <div class="collapse navbar-collapse" id="mainNavbarTheme">
                    <!--Navbar items-->
                    <ul class="navbar-nav ms-auto">
                        <li class="nav-item">
                            <a class="nav-link" href="#">Home</a>
                        </li>
                        <li class="nav-item">
                            <a class="nav-link" href="#">About</a>
                        </li>
                        <li class="nav-item dropdown">
                            <a class="nav-link dropdown-toggle" href="#" data-bs- toggle="dropdown">Dropdown Nav</a>
                            <div class="dropdown-menu dropdown-menu-end">
                                <a href="#" class="dropdown-item">Dropdown item</a>
                                <a href="#" class="dropdown-item">Dropdown item</a>
                                <a href="#" class="dropdown-item">Dropdown item</a>
                                <a href="#" class="dropdown-item">Dropdown item</a>
                            </div>
                        </li>
                        <li class="nav-item">
                            <a class="nav-link" href="#">Projects</a>
                        </li>
                        <li class="nav-item">
                            <a class="nav-link" href="#">Contact</a>
                        </li>
                    </ul>
                </div>
            </div>
        </nav>
    </header>