bootstrap 4：下拉菜单使导航栏拉伸

Question

我的下拉菜单有问题。我需要在我的导航栏右侧有一个下拉菜单。下拉菜单使导航栏拉伸，即增加它的高度。 .这是代码。

    <nav class="navbar navbar-dark  " style="background-color: #1B2D48;">
        <div class="container">
            <!-- Navbar brand -->
            <a class="navbar-brand" href="home.php">Home</a>
            <ul class="navbar-nav ml-auto" id="list-items" style="margin-right: 10px" ;>
                <li class="nav-item dropdown">
                    <a class="nav-link dropdown-toggle" href="#" id="navbarDropdown" role="button" data-toggle="dropdown" aria-haspopup="true" aria-expanded="false">
                        <?php echo $_SESSION['username']; ?>
                    </a>
                    <div class="dropdown-menu" aria-labelledby="navbarDropdown">
                        <a class="dropdown-item" href="#">Action</a>
                        <a class="dropdown-item" href="#">Another action</a>
                        <div class="dropdown-divider"></div>
                        <a class="dropdown-item" href="#">Something else here</a>
                    </div>
                </li>
            </ul>
            <!-- Collapse button -->
            <button class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarSupportedContent15" aria-controls="navbarSupportedContent15" aria-expanded="false" aria-label="Toggle navigation"><span class="navbar-toggler-icon"></span></button>

            <!-- Collapsible content -->
            <div class="collapse navbar-collapse" id="navbarSupportedContent15">

                <!-- Links -->
                <ul class="navbar-nav mr-auto text-right">

                    <li class="nav-item active">
                        <a class="nav-link" href="home.php">Home <span class="sr-only">(current)</span></a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="logout.php">Log out</a>
                    </li>
                </ul>
                <!-- Links -->

            </div>

            <!-- Collapsible content -->
        </div>
    </nav>