如何更改导航汉堡的颜色？

Question

我正在使用引导程序进行项目，但有件事在我的项目中造成了一个问题。我正在使用黑色和白色的渐变，并且在移动视图中，汉堡包图标的颜色为白色。我的问题是，如何在移动视图的引导程序导航栏中更改汉堡的颜色？

这是我的导航栏：

<nav class="navbar navbar-expand-lg navbar-dark bg-dark fixed-top">
        <div class="Container container">
            <a class="navbar-brand">
                <img src="images/feugerlogo.PNG" alt="Feuger Logo" class="Navbarlogoimage Navbarlogoimageheader">
            </a>
            <button id="hamburger" class="navbar-toggler" type="button" data-toggle="collapse" data-target="#navbarResponsive" aria-controls="navbarResponsive" aria-expanded="false" aria-label="Toggle navigation">
                <span class="navbar-toggler-icon"></span>
            </button>
            <div class="collapse navbar-collapse Navbaritems" id="navbarResponsive">
                <ul class="navbar-nav ml-auto">
                    <li class="nav-item active">
                        <a class="nav-link" href="index.html">Home</a>
                        <span class="sr-only">(current)</span>
                        </a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="#">About</a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="products.html">Products</a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="#">Services</a>
                    </li>
                    <li class="nav-item">
                        <a class="nav-link" href="#">Contact</a>
                    </li>
                </ul>
            </div>
        </div>