悬停改变颜色

Question

只是尝试在 CSS 中练习悬停和下拉菜单。在下面的代码中，我希望每当子下拉 div .li（带有 Home1 文本的绿色 div）悬停在上面时，ul（红色）的背景颜色应该变为蓝色。

非常感谢您的帮助。

html, body {
  margin: 0px;
  height: 100%;
  width: 100%;
  left: 0px;
  top: 0px;
  background-color: rgba(0,0,0,1);
  padding: 0px;
}

* {
  box-sizing: border-box;
}

a {
  color: rgba(0,0,0,1);
  text-decoration: none;
  /* [disabled]background-color: rgba(255,0,0,1); */
  display: block;
}

li {
  display: block;
  width: 100px;
  background-color: rgba(0,255,0,1);
  border: thin solid rgba(0,0,0,1);
  position: relative;
  margin-right: auto;
  margin-left: auto;
  /* [disabled]left: 0px; */
  /* [disabled]top: 0px; */
  margin-top: 5px;
  /* [disabled]float: left; */
  list-style-type: none;
}

a:hover {
  color: rgba(255,0,0,1);
}

.wrapper {
  height: 600px;
  max-width: 960px;
  margin-left: auto;
  left: 0px;
  top: 0px;
  background-color: rgba(204,204,204,1);
  margin-right: auto;
  position: relative;
  padding: 0px;
  margin-top: 0px;
}

.content {
  position: relative;
  box-sizing: border-box;
  height: 100%;
  max-height: 200px;
  max-width: 600px;
  background-color: #FFF;
  margin-right: auto;
  margin-left: auto;
  margin-top: 0px;
  left: 0px;
  right: 0px;
  font-size: 32px;
  text-align: center;
  border: 3px solid rgba(0,0,0,1);
  border-radius: 15px 15px 0px 0px;
  width: 100%;
}

.content-small {
  max-width: 100px;
  height: 100%;
  max-height: 50px;
  background-color: rgba(0,255,204,1);
  position: relative;
  margin-right: auto;
  margin-left: auto;
  border: 3px solid rgba(0,0,0,1);
  top: 5px;
  margin-top:10px;
}

.content-small:hover + .dropdown {
  visibility: visible;    
}

.dropdown:hover {
  visibility: visible;
}

ul {
  position: relative;
  background-color: rgba(255,0,0,1);
  max-width: 500px;
  list-style-type: none;
  margin-left: auto;
  margin-right: auto;
  height: auto;
  padding: 0;
  margin-top: 0px;
}

.dropdown {
  max-width: 500px;
  /* [disabled]max-height: 100px; */
  position: relative;
  margin-right: auto;
  margin-left: auto;
  top: 0px;
  margin-top: 5px;
  visibility: hidden;
  list-style-type: none;
  text-align: center;
  background-color: rgba(153,153,153,1);
}

<div class="wrapper">
  <div class="content">
    <div class="content-small">
      Home
    </div>
    <div class="dropdown">
      <ul>
        <li><a href="">Home1</a></li>
        <li><a href="">Home2</a></li>
      </ul>
    </div>
  </div>
</div>

Answer 1

我认为 Javascript 是这里的简单解决方案。

如果要设置父元素的颜色，CSS 没有可用的当前选择器。

$('.dropdown li').mouseenter(function(){
  $(this).parent().css('background-color', 'blue');
});

$('.dropdown li').mouseleave(function(){
  $(this).parent().css('background-color', 'red');
});

html,body {
    margin: 0px;
    height: 100%;
    width: 100%;
    left: 0px;
    top: 0px;
    background-color: rgba(0,0,0,1);
    padding: 0px;
    }


*{
    box-sizing:border-box;
}

a {
	color: rgba(0,0,0,1);
	text-decoration: none;
	/* [disabled]background-color: rgba(255,0,0,1); */
	display: block;
}

li {
	display: block;
	width: 100px;
	background-color: rgba(0,255,0,1);
	border: thin solid rgba(0,0,0,1);
	position: relative;
	margin-right: auto;
	margin-left: auto;
	/* [disabled]left: 0px; */
	/* [disabled]top: 0px; */
	margin-top: 5px;
	/* [disabled]float: left; */
	list-style-type: none;
}

a:hover {
	color: rgba(255,0,0,1);
}




.wrapper {
    height: 600px;
    max-width: 960px;
    margin-left: auto;
    left: 0px;
    top: 0px;
    background-color: rgba(204,204,204,1);
    margin-right: auto;
    position: relative;
    padding: 0px;
    margin-top: 0px;
}


.content {
    position: relative;
    box-sizing: border-box;
    height: 100%;
    max-height: 200px;
    max-width: 600px;
    background-color: #FFF;
    margin-right: auto;
    margin-left: auto;
    margin-top: 0px;
    left: 0px;
    right: 0px;
    font-size: 32px;
    text-align: center;
    border: 3px solid rgba(0,0,0,1);
    border-radius: 15px 15px 0px 0px;
    width: 100%;
}

.content-small {
    max-width: 100px;
    height: 100%;
    max-height: 50px;
    background-color: rgba(0,255,204,1);
    position: relative;
    margin-right: auto;
    margin-left: auto;
    border: 3px solid rgba(0,0,0,1);
    top: 5px;
  margin-top:10px;
}

.content-small:hover + .dropdown{
    visibility: visible;    
}

.dropdown:hover{
	visibility: visible;
}

ul {
	position: relative;
	background-color: rgba(255,0,0,1);
	max-width: 500px;
	list-style-type: none;
	margin-left: auto;
	margin-right: auto;
	height: auto;
	padding: 0;
	margin-top: 0px;
}

.dropdown {
	max-width: 500px;
	/* [disabled]max-height: 100px; */
	position: relative;
	margin-right: auto;
	margin-left: auto;
	top: 0px;
	margin-top: 5px;
	visibility: hidden;
	list-style-type: none;
	text-align: center;
	background-color: rgba(153,153,153,1);
}

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div class="wrapper">
	<div class="content">
	  <div class="content-small">
		Home
        </div>
	<div class="dropdown">
      <ul>
<li><a href="">Home1</a></li>
<li><a href="">Home2</a></li>
		</ul>
      </div>
     
</div>

</div>

Answer 2

如果您坚持使用纯 CSS 解决方案，您可以考虑巧妙地设计和定位 :pseudo 元素。

CSS

.dropdown li {
    width: 100%;
    background: transparent;
    border: 0px;
    position: relative;
    z-index: 9;
}

.dropdown li a {
    max-width: 100px;
    display: block;
    margin: auto;
    background-color: rgba(0,255,0,1);
    border: thin solid rgba(0,0,0,1);
    z-index: 9;
    position: relative;
}

.dropdown li:hover {
    background: blue;
    z-index: 8;
}

.dropdown li:hover:before {
    position: absolute;
    content: "";
    background: blue;
    top: -100px;
    bottom: -100px;
    left: 0;
    width: 100%;
}

.dropdown ul {
    overflow: hidden;
}

/* Start Added Styles */

.dropdown li {
    width: 100%;
    background: transparent;
    border: 0px;
    position: relative;
    z-index: 9;
}

.dropdown li a {
    max-width: 100px;
    display: block;
    margin: auto;
    background-color: rgba(0,255,0,1);
    border: thin solid rgba(0,0,0,1);
    z-index: 9;
    position: relative;
}

.dropdown li:hover {
    background: blue;
    z-index: 8;
}

.dropdown li:hover:before {
    position: absolute;
    content: "";
    background: blue;
    top: -100px;
    bottom: -100px;
    left: 0;
    width: 100%;
}

.dropdown ul {
    overflow: hidden;
}

/* End Added Styles */

html,body {
    margin: 0px;
    height: 100%;
    width: 100%;
    left: 0px;
    top: 0px;
    background-color: rgba(0,0,0,1);
    padding: 0px;
    }


*{
    box-sizing:border-box;
}

a {
	color: rgba(0,0,0,1);
	text-decoration: none;
	/* [disabled]background-color: rgba(255,0,0,1); */
	display: block;
}

li {
	display: block;
	width: 100px;
	background-color: rgba(0,255,0,1);
	border: thin solid rgba(0,0,0,1);
	position: relative;
	margin-right: auto;
	margin-left: auto;
	/* [disabled]left: 0px; */
	/* [disabled]top: 0px; */
	margin-top: 5px;
	/* [disabled]float: left; */
	list-style-type: none;
}

a:hover {
	color: rgba(255,0,0,1);
}




.wrapper {
    height: 600px;
    max-width: 960px;
    margin-left: auto;
    left: 0px;
    top: 0px;
    background-color: rgba(204,204,204,1);
    margin-right: auto;
    position: relative;
    padding: 0px;
    margin-top: 0px;
}


.content {
    position: relative;
    box-sizing: border-box;
    height: 100%;
    max-height: 200px;
    max-width: 600px;
    background-color: #FFF;
    margin-right: auto;
    margin-left: auto;
    margin-top: 0px;
    left: 0px;
    right: 0px;
    font-size: 32px;
    text-align: center;
    border: 3px solid rgba(0,0,0,1);
    border-radius: 15px 15px 0px 0px;
    width: 100%;
}

.content-small {
    max-width: 100px;
    height: 100%;
    max-height: 50px;
    background-color: rgba(0,255,204,1);
    position: relative;
    margin-right: auto;
    margin-left: auto;
    border: 3px solid rgba(0,0,0,1);
    top: 5px;
  margin-top:10px;
}

.content-small:hover + .dropdown{
    visibility: visible;    
}

.dropdown:hover{
	visibility: visible;
}

ul {
	position: relative;
	background-color: rgba(255,0,0,1);
	max-width: 500px;
	list-style-type: none;
	margin-left: auto;
	margin-right: auto;
	height: auto;
	padding: 0;
	margin-top: 0px;
}

.dropdown {
	max-width: 500px;
	/* [disabled]max-height: 100px; */
	position: relative;
	margin-right: auto;
	margin-left: auto;
	top: 0px;
	margin-top: 5px;
	visibility: hidden;
	list-style-type: none;
	text-align: center;
	background-color: rgba(153,153,153,1);
}

<div class="wrapper">
	<div class="content">
	  <div class="content-small">
		Home
        </div>
	<div class="dropdown">
      <ul>
<li><a href="">Home1</a></li>
<li><a href="">Home2</a></li>
		</ul>
      </div>
     
</div>

</div>

您可能需要相应地调整值以满足您的要求。

免责声明
这有点小技巧，你有责任彻底测试它。此答案的目的是展示您需要达到的程度才能仅使用 CSS 来实现这一目标。

虽然，@randy 说父元素不能通过逻辑 CSS 样式以这种方式接近是正确的。如果您不愿意像上面那样探索打破常规的替代方案，那么 javascript 确实是您唯一的解决方案。