前端——css浮动的影响与清除

子元素如果是浮动元素，那父元素一般不设置高度，可能造成布局混乱以后更改麻烦，不设置高度也会出现混乱

<div class="father">
		<div class="box1"></div>
		<div class="box2"></div>
		<div class="box3"></div>
	</div>

	<div class="father2"></div>

*{
			padding: 0;
			margin: 0;

		}
		.father{
			width: 1126px;
			height: 300px;

		}
		.box1{
			width: 200px;

			height: 500px;
			float: left;
			background-color: red;
		}
		.box2{
			width: 300px;
			height: 200px;
			float: left;
			background-color: green;
		}
		.box3{
			width: 400px;
			float: left;
			height: 100px;
			background-color: blue;
		}
		.father2{
			width: 1126px;
			height: 600px;
			background-color: purple;
		}

消除影响

内墙法

用的少，在浮动元素最后加个div设置为clear:both清除浮动带来的影响

		*{
			padding: 0;
			margin: 0;

		}
		.father{
			width: 1126px;

		}
		.box1{
			width: 200px;

			height: 500px;
			float: left;
			background-color: red;
		}
		.box2{
			width: 300px;
			height: 200px;
			float: left;
			background-color: green;
		}
		.box3{
			width: 400px;
			float: left;
			height: 100px;
			background-color: blue;
		}
        .clear{
            clear: both;
        }
		.father2{
			width: 1126px;
			height: 600px;
			background-color: purple;
		}
	</style>
</head>
<body>

	<div class="father">
		<div class="box1"></div>
		<div class="box2"></div>
		<div class="box3"></div>
        <!-- 给浮动元素最后面加一个空的div 并且该元素不浮动 ，然后设置clear:both-->
			<!-- 内墙法 -->
			<!-- 无缘无故加了div元素  结构冗余 -->
        <div class="clear"></div>

	</div>

	<div class="father2"></div>


</body>
</html>

伪元素清除法

利用伪元素after，在父元素后添加空内容，转换成块元素，本质还是在父元素内加了块元素。

<div class="clearfix">
		<div class="box1"></div>
		<div class="box2"></div>
		<div class="box3"></div>

	</div>

	<div class="div2"></div>

*{
			padding: 0;
			margin: 0;

		}
		.clearfix{
			width: 1126px;

		}
		.box1{
			width: 200px;

			height: 300px;
			float: left;
			background-color: red;
		}
		.box2{
			width: 300px;
			height: 100px;
			float: left;
			background-color: green;
		}
		.box3{
			width: 400px;
			float: left;
			height: 50px;
			background-color: blue;
		}
		
/*必须要写这三句*/
       .clearfix:after{
           content:'';
           clear:both;
           display:block;
       }
  
       
/*也这么写
.clearfix:after{
			content: '.';
			clear: both;
			display: block;
			height: 0;
			visibility: hidden;
*/

		.div2{
			width: 1126px;
			height: 400px;
			background-color: purple;
		}

overflow:hidden

<div class="div1">
	<div class="box1"></div>
	<div class="box2"></div>
	<div class="box3"></div>

</div>

<div class="div2"></div>

https://blog.youkuaiyun.com/weixin_42359436/article/details/81183326