4.CSS中float导致的高度坍塌问题及解决方法

高度坍塌:浮动元素布局导致的问题

高度坍塌的根源:浮动盒子脱离了常规流,因此常规流盒子进行高度计算时,不会考虑浮动盒子的高度。

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container{
            padding:30px;
            background-color:blue;
        }
        .sub{
            height:100px;
            width:100px;
            margin:10px;
            float:left;
            background-color: red;
        }
    </style>
</head>
<body>
    <div class="container">
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
    </div>
</body>
</html>

index.html

效果展示:

.container的div元素没有将10个.sub的div元素包裹。

解决方法:

清除浮动,涉及CSS属性:clear

clear:默认值为none,不清除浮动

clear:both,清除左右浮动,该元素必须出现在所有浮动盒子的下方

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <style>
        .container {
            padding: 30px;
            background-color: blue;
        }

        .sub {
            height: 100px;
            width: 100px;
            margin: 10px;
            float: left;
            background-color: red;
        }

        .clearfix::after {
            content: "";
            display: block;
            clear: both;
        }
    </style>
</head>

<body>
    <div class="container clearfix">
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
        <div class="sub"></div>
    </div>
</body>

</html>

index.html

效果展示:

(0)

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