sidebar.php

<nav class="sb-sidenav accordion sb-sidenav-dark" id="sidenavAccordion">
    <div class="sb-sidenav-menu">
        <div class="nav">
            <div class="sb-sidenav-menu-heading">
                Main
            </div>
            <a class="nav-link" href="<?php echo site_url('admin') ?>">
                <div class="sb-nav-link-icon">
                    <i class="fas fa-tachometer-alt"></i>
                </div>
                Overview
            </a>
            <a class="nav-link collapsed" href="#" data-toggle="collapse" data-target="#collapseLayouts" aria-expanded="false" aria-controls="collapseLayouts">
                <div class="sb-nav-link-icon">
                    <i class="fas fa-fw fa-boxes"></i>
                </div>
                Products
                <div class="sb-sidenav-collapse-arrow">
                    <i class="fas fa-angle-down"></i>
                </div>
            </a>
            <div class="collapse" id="collapseLayouts" aria-labelledby="headingOne" data-parent="#sidenavAccordion">
                <nav class="sb-sidenav-menu-nested nav">
                    <a class="nav-link" href="<?php echo site_url('admin/products/add') ?>">
                        New Product
                    </a>
                    <a class="nav-link" href="<?php echo site_url('admin/products') ?>">
                        List Product
                    </a>
                </nav>
            </div>

            <div class="sb-sidenav-menu-heading">
                Settings
            </div>
            <a class="nav-link" href="#">
                <div class="sb-nav-link-icon">
                    <i class="fas fa-fw fa-users"></i>
                </div>
                Users
            </a>
            <a class="nav-link" href="#">
                <div class="sb-nav-link-icon">
                    <i class="fas fa-fw fa-cog"></i>
                </div>
                Settings
            </a>
        </div>
    </div>
    <div class="sb-sidenav-footer">
        <div class="small">
            Logged in as:
        </div>
        Admin
    </div>
</nav>