下拉菜单及其滚动条无法正常工作

Question

我的汉堡包菜单及其scorll栏无法正常工作。当窗口高度低于一定数量的像素时，我无法再滚动到汉堡菜单的底部。看看我的代码：

CSS

.fill {
    color: grey;
    height: 8000px;
}

body {
    margin: 0;
    padding: 0;
    font-family: 'Arial', serif;
    color: #605b41;
}

li {
    list-style: none;
}

nav {
    z-index: 500;
    background-color: #fff;
    position: fixed;
    width: 100%;
    max-height: 220px;
}

.navigation-bar-top-mobile {
    background: white;
    width: 100%;
    color: #0E8DBD;
    color: white;
    box-shadow: 0 8px 6px -6px grey;
    overflow: auto;
}





.navigation-bar-top a {
    text-decoration: none;
    color: #0E8DBD;
} 


header,nav, img, li{
    transition: all 0.6s;
    -moz-transition: all 0.6s; 
    -webkit-transition: all 0.6s; 
}

header.large{
    height: 0px;
}
header.large img { 
    width: 237px; height: 120px;
}

header.small { 
    height: 50px; 
}
header.small img{ 
    width: 170px; height: 90px; margin-top: -10px; 
}



.left {
    float: left;
    padding-left: 50px;
    padding-bottom: 10px;
}

.right {
    float: right;
}

.newboxes {
    display: none;
    padding-top: 10px;
}

.dropdown-hamburger {
    width: 100%;
    padding-left: 55px;
    padding-right: 55px;
    padding-bottom: 30px;
    max-height: 400px;
        overflow-x: hidden;
}

.dropdown-hamburger span {
    color: #3176bb;
    display: block;
    padding: 5px 0;
}

.dropdown-hamburger hr {
    border-color: #3176bb;
    margin: 10px 0;
}

.dropdown-hamburger-content {
    padding-top: 140px;
    overflow-x: hidden;
    width: 100%;
}

.dropdown-hamburger-content-style span {
    font-size: 17px;
    padding-left: 20px;
}

.mobile-nav {
    display: inline;
    font-size: 20px;
    color: red;
}



/*media*/









@media all and (max-width: 1000px) {
    .navigation-bar-top ul {
        display: none;
    }
}

@media all and (max-width: 1000px) {
    .desktop-nav {
        display: none;
    }
}

@media all and (min-width: 1001px) {
    .mobile-nav  {
        display: none;
    }
}

JS

function showonlyone(thechosenone) {
    $('.newboxes').each(function(index) {
      if ($(this).attr("id") == thechosenone) {
           $(this).toggle();
      }
      else {
           $(this).hide();
      }
    });
    }

    $( document ).ready(function() {

        $( ".dropdown-hamburger-content" ).hide();
        $( ".right" ).click(function() {
        $( ".hamburger" ).toggle( function() {
        });
        });

        $( ".right" ).click(function() {
        $( ".dropdown-hamburger-content" ).toggle( function() {
        $( ".dropdown-hamburger" ).show();
        });
        });

        });



    /*-----*/




/*image resize top nav */

    $(document).on("scroll",function(){
        if($(document).scrollTop()>20){
            $("header").removeClass("large").addClass("small");
        } else{
            $("header").removeClass("small").addClass("large");
        }
    });

    /*-----*/




    $(document).ready(function(){

        $(".burger-nav").on("click", function(){

            $("burger-nav ul").toggleClass("open");
        })

    });

HTML

<nav>
                    <header class=“large”>
                    <div class="navigation-bar-top-mobile ">
                        <div class="mobile-nav">
                            <br>
                            <div class="images">
                            <div class="left"><a href="#"><img class="logo" src="images/logo.png"></a></div>
                            <div class="right"><a><img src="https://imgur.com/a/3ov6t"></a></div>
                            <div class="dropdown-hamburger">
                                <div class="dropdown-hamburger-content">
                                    <a id="" href="javascript:showonlyone('newboxes5');"><span>Placeholder1</span></a>
                                    <div class="newboxes" id="newboxes5">
                                        <div class="dropdown-hamburger-content-style">
                                            <hr>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                        </div>
                                    </div>
                                    <hr>
                                    <a id="" href="javascript:showonlyone('newboxes6');"><span>Placeholder2</span></a>
                                    <div class="newboxes" id="newboxes6">
                                        <div class="dropdown-hamburger-content-style">
                                            <hr>

                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                        </div>
                                    </div>
                                    <hr>
                                    <a id="" href="javascript:showonlyone('newboxes7');"><span>Placeholder3</span></a>
                                    <div class="newboxes" id="newboxes7">
                                        <div class="dropdown-hamburger-content-style">
                                            <hr>

                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                        </div>
                                    </div>
                                    <hr>
                                    <a id="" href="javascript:showonlyone('newboxes8');"><span>Placeholder4</span></a>
                                    <div class="newboxes" id="newboxes8">
                                        <div class="dropdown-hamburger-content-style">
                                            <hr>

                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                            <a href="#"><span>Placeholder</a></span>
                                        </div>
                                    </div>
                                    <hr>
                                    <a href="#"><span>Placeholder5</span></a>
                                    <hr>
                                </div>
                        </div>
                    </div>
                </nav>

调整浏览器大小以查看平板电脑导航栏。然后单击右上角以打开汉堡菜单。这就是问题所在。 我还提供了一些与我遇到的问题无关的代码，但是为了以防万一。

感谢您的时间。