navbar.php

<nav class="sb-topnav navbar navbar-expand navbar-dark bg-primary">
    <a class="navbar-brand mr-1" href="<?php echo site_url('admin') ?>"><?php echo SITE_NAME ?></a>
    <button class="btn btn-link btn-sm text-white order-1 order-sm-0" id="sidebarToggle" href="#">
        <i class="fas fa-bars"></i>
    </button>

    <!-- Navbar Search-->
    <form class="d-none d-md-inline-block form-inline ml-auto mr-0 mr-md-3 my-2 my-md-0">
        <div class="input-group">
            <input class="form-control" type="text" placeholder="Search for..." aria-label="Search" aria-describedby="basic-addon2" />
            <div class="input-group-append">
                <button class="btn btn-light" type="button"><i class="fas fa-search"></i></button>
            </div>
        </div>
    </form>

    <!-- Navbar-->
    <ul class="navbar-nav ml-auto ml-md-0">
        <li class="nav-item dropdown no-arrow mx-1">
            <a class="nav-link dropdown-toggle" id="userDropdown" href="#" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                <i class="fas fa-bell fa-fw"></i>
                <span class="badge badge-danger">9+</span>
            </a>
            <div class="dropdown-menu dropdown-menu-right" aria-labelledby="userDropdown">
                <a class="dropdown-item" href="#">User</a>
                <a class="dropdown-item" href="#">Activity Log</a>
                <div class="dropdown-divider"></div>
                <a class="dropdown-item" href="login.html">Logout</a>
            </div>
        </li>
        <li class="nav-item dropdown no-arrow mx-1">
            <a class="nav-link dropdown-toggle" id="messagesDropdown" href="#" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                <i class="fas fa-envelope fa-fw"></i>
                <span class="badge badge-danger">9+</span>
            </a>
            <div class="dropdown-menu dropdown-menu-right" aria-labelledby="messagesDropdown">
                <a class="dropdown-item" href="#">Message</a>
                <a class="dropdown-item" href="#">Activity Log</a>
                <div class="dropdown-divider"></div>
                <a class="dropdown-item" href="login.html">Logout</a>
            </div>
        </li>
        <li class="nav-item dropdown no-arrow mx-1">
            <a class="nav-link dropdown-toggle" id="messagesDropdown" href="#" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                <i class="fas fa-user-circle fa-fw"></i> Admin
            </a>
            <div class="dropdown-menu dropdown-menu-right" aria-labelledby="messagesDropdown">
                <a class="dropdown-item" href="#">Message</a>
                <a class="dropdown-item" href="#">Activity Log</a>
                <div class="dropdown-divider"></div>
                <a class="dropdown-item" href="<?= site_url('admin/login/logout') ?>">Logout</a>
            </div>
        </li>
    </ul>
</nav>