高度坍塌及解决-CFANZ编程社区

如下代码：

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .d1{
            background-color: blanchedalmond;
            width: 500px;
            padding: 20px;
            
        }
        .d2{
            background-color: red;
            float: left;
            width: 100px;
            height: 100px;
            border: 2px solid;
            margin: 10px 10px;
        }
    </style>
</head>
<body>
    <div class="d1">
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
    </div>
</body>
</html>

页面显示效果：

我们可以看到，第一个div的高度为0

产生原因：常规流盒子的自动高度（由内容而定），在计算时，不会考虑浮动盒子。

解决办法：清除浮动，使用clear属性，其值可为left，right，both，默认为none

1、写一个div 放最后

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .d1{
            background-color: blanchedalmond;
            width: 500px;
            padding: 20px;
            
        }
        .d2{
            background-color: red;
            float: left;
            width: 100px;
            height: 100px;
            border: 2px solid;
            margin: 10px 10px;
        }
    </style>
</head>
<body>
    <div class="d1">
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div style="clear: both;"></div>
    </div>
</body>
</html>

2、伪元素选择器::after

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .d1{
            background-color: blanchedalmond;
            width: 500px;
            padding: 20px;
            
        }
        .d2{
            background-color: red;
            float: left;
            width: 100px;
            height: 100px;
            border: 2px solid;
            margin: 10px 10px;
        }
        .clear-fix::after{
            content:"";
            display:block;
            clear:both;
        }
    </style>
</head>
<body>
    <div class="d1 clear-fix">
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
        <div class="d2"></div>
    </div>
</body>
</html>

页面显示效果：

在使用浮动时，经常会遇到高度坍塌，一定要记得清除浮动。