带有 CSS 过渡 Z-Index 的 CSS 下拉菜单不起作用

Question

我无法让z-index 在主页上的主要英雄图片上方显示我的下拉菜单。

访问网站是：auldlangsynegoods.com。我希望有人可以使用一些开发工具来查看该站点并找出为什么这个下拉菜单没有出现。

这是干净简单的html：

<nav id="mainNav" role="navigation" class="cf">
    <h2>Site navigation</h2>
    <ul class="topMenu">
      <li class="hover">
        <h3>Infant and Baby</h3>
        <ul class="subMenu">
          <li><a href="shoes_and_accessories.html" title="Infant and Baby Shoes">Shoes</a></li>
          <li><a href="shoes_and_accessories.html" title="Infant and Baby Hats">Hats</a></li>
          <li><a href="shoes_and_accessories.html" title="Infant and Baby Clothing">Clothing</a></li>
        </ul>
      </li>
      <li><a href="millinery.html" title="Millinery Also Known as Hats">Millinery</a></li>
      <li class="hover">
        <h3>Shoes and Accessories</h3>
        <ul class="subMenu">
          <li><a href="shoes_and_accessories.html" title="Shoes and Accessories - Mens Shoes">Mens Shoes</a></li>
          <li><a href="shoes_and_accessories.html" title="Shoes and Accessories - Womens Shoes">Womens Shoes</a></li>
          <li><a href="shoes_and_accessories.html" title="Shoes and Accessories - Bags">Bags</a></li>
        </ul>
      </li>
      <li class="hover">
        <h3>Organic Skincare</h3>
        <ul class="subMenu">
          <li><a href="Organic_Skincare.html" title="Organic Skincare - Body">Body</a></li>
          <li><a href="shoes_and_accessories.html" title="Organic Skincare - Face">Face</a></li>
        </ul>
      </li>
      <li><a href="Garments.html" title="Garments">Garments</a></li>
    </ul>
  </nav>

这是桌面视图的简单干净的 CSS：

/*nav styles*/
#mainNav {
    padding-left:3.9%;
    margin-bottom: 1.5em;
}

#mainNav li {
    float: left;
}

#mainNav a {

    display: block;
    color: #383420;
    border: none;
}

#mainNav a:hover {
    color: #484329;
}

#mainNav a.current {
    color: #A6A6A6;
    cursor: default;
}
/*nav styles*/
#mainNav {
    padding-left: 3.9%;
    margin-bottom:1em;
}
#mainNav li {
    margin-right: 3%;
    position: relative;
}
#mainNav a, #mainNav h3 {
    font-size: 1.2em;
    text-align: left;
    padding: 0 1em;
}
/*dropdown menu styles*/
#mainNav ul.subMenu {
    float: none;
    width: auto;
    height: auto;
    position: absolute;
    top: 0;
    padding-top: 2.8em;
    left: -8000em;
    max-height: 0;
    -moz-transition:max-height 0.5s ease;
    -webkit-transition:max-height 0.5s ease;
    -o-transition:max-height 0.5s ease;
    transition:max-height 0.5s ease;
    overflow: hidden;
    z-index: 5;
}
#mainNav ul.subMenu li {
    float: none;
    margin: 0;
    background: rgb(76, 67, 65);
    background: rgba(76, 67, 65, .9);
}
#mainNav li:hover ul {
    left: 0;
    max-height: 20em;
}
#mainNav ul.subMenu li a {
    border-bottom: 1px solid white;
    padding: .2em 1em;
    white-space: nowrap;
    color: white;
    text-align: left;
    font-size: 1.1em;
}
#mainNav ul.subMenu li:last-child a {
    border-bottom: none;
}
#mainNav ul.subMenu li a:hover {
    background: rgb(123, 121, 143);
}

Answer 1

在您提供的网站上，z-index 似乎不是问题，而是您需要从以下位置删除 overflow: hidden;：

#mainNav {
    overflow: hidden;
    margin-bottom: 1.5em;
}

使用 chrome web 开发工具删除该样式后，我能够看到下拉列表。