CSS 悬停一个元素，然后更改另一个元素（不使用 Javascript）
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Hover one element, and change another (without using Javascript)
提问by Arlington
I have a nested CSS menu that I can't get the submenus to come up.
我有一个嵌套的 CSS 菜单，无法显示子菜单。
I took the code from A list apart. The example on that site works perfectly fine, but since I have 2 CSS navigational menus on my page, I have to put my HTML elements in different CSS classes.
我把A list 中的代码分开了。该站点上的示例运行良好，但由于我的页面上有 2 个 CSS 导航菜单，因此我必须将 HTML 元素放在不同的 CSS 类中。
Here is my code:
这是我的代码：
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN"
"http://www.w3.org/TR/html4/strict.dtd">
<html>
<head>
<style type="text/css">
ul#lvl1 {
margin:0;
padding:0;
list-style:none;
width:150px; /* Width of Menu Items */
border-bottom:1px solid #ccc;
}
li.lvl1 {position:relative}
ul.lvl2 {
position: absolute;
left: 149px; /* Set 1px less than menu width */
top: 0;
display: none;
}
/* Styles for Menu Items */
li.lvl1 > a {
display: block;
text-decoration: none;
color: #777;
background: #fff; /* IE6 Bug */
padding: 5px;
border: 1px solid #ccc;
border-bottom: 0;
}
/* Fix IE. Hide from IE Mac \*/
* html.lvl1 > ul > li {float:left;height:1%}
* html.lvl1 > ul > li > a {height:1%}
/* End */
li.lvl2 > a:hover { color: #E2144A; background: #f9f9f9; } /* Hover Styles */
li.lvl2 > a { padding: 2px 5px; } /* Sub Menu Styles */
a.lvl1:hover ul.lvl2 {display: block} /* The magic */
</style>
</head>
<body>
<ul id="lvl1">
<li class="lvl1">
<a class="lvl1" href="#">item1</a>
<ul class="lvl2">
<li class="lvl2">
<a class="lvl2" href="#">subitem1</a>
</li>
</ul>
</li>
<li class="lvl1">
<a class="lvl1" href="#">item2</a>
<ul class="lvl2">
<li class="lvl2">
<a class="lvl2" href="#">subitem2</a>
</li>
</ul>
</li>
</ul>
</body>
</html>
Now when I hover over the "a" on level 1, the "ul" on level 2 won't come up. Can someone please shed some light? I may be missing something obvious. Thanks!
现在，当我将鼠标悬停在第 1 级的“a”上时，第 2 级的“ul”不会出现。有人可以透露一些信息吗？我可能遗漏了一些明显的东西。谢谢！
回答by Cristian Necula
You must change your CSS selector to target the lvl2 <ul>, since it is not nested anymore (it's a sibling, so use +).
您必须更改 CSS 选择器以定位 lvl2 <ul>，因为它不再嵌套（它是兄弟，所以使用 +）。
a.lvl1:hover + ul.lvl2 {display: block} /* The magic */
You should read this list of css selectors.
您应该阅读此 css 选择器列表。
Or you could move the hover on the lvl1 <li>, instead of the anchor
或者您可以将悬停移动到 lvl1 上<li>，而不是锚点上
li.lvl1:hover ul.lvl2 {display: block} /* The magic */
