我正在制作一个响应式顶部导航栏，在较小的屏幕上查看时会垂直堆叠。我的问题是，在移动视图中，当您将鼠标悬停在导航项上以展开下拉菜单时，下拉菜单会覆盖其他导航链接。
当导航链接悬停在上方时，我正在尝试使下部导航元素向下移动以为下拉菜单腾出空间。我想避免使用 jQuery 或 Bootstrap，并且尽可能只使用 HTML 和 CSS。
JSFiddle 链接（一定要在手机上调整窗口或视图的大小）： https ://jsfiddle.net/adilworth/fzrnvukm/3/
我尝试过什么：我已经广泛尝试更改 CSS 位置元素，但我似乎无法让它按我想要的方式运行。
HTML：
<ul id="navigation">
<li><a href="#">Product 1</a>
<ul>
<li><a href="#">rx.com </a></li>
<li><a href="#">Resources</a></li>
<li><a href="#">Copay Cards</a></li>
</ul>
</li>
<li><a href="#">Product 2</a>
<ul>
<li><a href="#">e.com </a></li>
<li><a href="#">Resources</a></li>
<li><a href="#">Copay Cards</a></li>
<li><a href="#">Informational Video</a></li>
</ul>
</li>
<li><a href="#">INSOMNIA EDUCATION</a>
<ul>
<li><a href="#">Complete Night Sleep Resources</a></li>
<li><a href="#">sleep.com </a></li>
</ul>
</li>
<li><a href="#">PAIN MGMT EDUCATION</a>
<ul>
<li><a href="#">Safer Pain Management Resources</a></li>
<li><a href="#">painmanagement.com </a></li>
</ul>
</li>
<li><a href="#">MEDICAL AFFAIRS</a>
<ul>
<li><a href="#">Request Clinical Reprints</a></li>
<li><a href="#">Schedule a Scientific Session </a></li>
</ul>
</li>
</ul>
CSS：
/* Main Navigation */
#nav {
position:relative;
width:620px;
margin:0 auto;
margin-top:50px;
padding:10px;
}
ul#navigation {
margin:0px auto;
position:relative;
float:left;
}
ul#navigation li {
display:inline;
font-size:12px;
font-weight:bold;
margin:0;
padding:0;
float:left;
position:relative;
}
ul#navigation li a {
width: 234px;
padding:10px 25px;
color: black;
text-decoration:none;
display:inline-block;
background: #ebebeb;
}
ul#navigation li a:hover {
background:#ebebeb;
color:black;
}
ul#navigation li a.first {
border-left: 0 none;
}
ul#navigation li a.last {
border-right: 0 none;
}
ul#navigation li:hover > a {
background:#ebebeb;
}
/* Drop-Down Navigation */
ul#navigation li:hover > ul
{
/*these 2 styles are very important,
being the ones which make the drop-down to appear on hover */
visibility:visible;
opacity:1;
}
ul#navigation ul, ul#navigation ul li ul {
list-style: none;
margin: 0;
padding: 0;
/*the next 2 styles are very important,
being the ones which make the drop-down to stay hidden */
visibility:hidden;
opacity:0;
position: absolute;
z-index: 99999;
width:234px;
background:#ebebeb;
}
ul#navigation ul {
top: 43px;
left: 1px;
}
ul#navigation ul li ul {
top: 0;
left: 181px; /* strong related to width:180px; from above */
}
ul#navigation ul li {
clear:both;
width:55px;
}
ul#navigation ul li a {
background:none;
padding:7px 15px;
color:#black;
text-decoration:none;
display:inline-block;
border:0 none;
float:left;
clear:both;
width:150px;
}