CSS布局原理与实现

实例演示如何消除子元素浮动造成父元素高度折叠的影响

实例

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>Document</title>
    <style>
        #div1 {
            width: 300px;
            border: 4px dashed #f90;
            /* display: inline-block; */
            overflow: hidden;
        }
        
        #div2 {
            width: 300px;
            height: 400px;
            background-color: aqua;
            float: left;
        }
    </style>
</head>

<body>
    <div id="div1">
        <div id="div2"></div>
    </div>
</body>

</html>

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2. 实例演示三列布局的实现原理( 绝对定位实现, 浮动定位实现)

实例绝对定位

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>三列布局-绝对定位</title>
    <style>
        .header,
        .footer {
            width: 1000px;
            height: 50px;
            background-color: aliceblue;
            margin: 0 auto;
        }
        
        .main {
            width: 1000px;
            background-color: aquamarine;
            margin: 10px auto;
            
            position: relative;
        }
        .left{
            width:200px;
            min-height: 800px;
            background-color: bisque;

            position: absolute;
            left:0;
            top:0;
        }
        .content{
            min-height: 800px;
            background-color:lawngreen;

            margin: 0 200px;
        }
        .right{
            width:200px;
            min-height: 800px;
            background-color:lightcoral;

            position: absolute;
            right:0;
            top:0;
        }
    </style>
</head>

<body>
    <div class="header">header</div>
    <div class="main">
        <div class="left">left</div>
        <div class="content">content</div>
        <div class="right">right</div>
    </div>
    <div class="footer">footer</div>
</body>

</html>

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实例浮动定位

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <meta http-equiv="X-UA-Compatible" content="ie=edge">
    <title>三列布局-浮动定位</title>
    <style>
        .header,
        .footer {
            width: 1000px;
            height: 50px;
            background-color: aliceblue;
            margin: 0 auto;
        }
        
        .main {
            width: 1000px;
            background-color: aquamarine;
            margin: 10px auto;
            overflow: hidden;
        }
        
        .left {
            width: 200px;
            min-height: 800px;
            background-color: bisque;
            float: left;
        }
        
        .content {
            width: 600px;
            min-height: 800px;
            background-color: lawngreen;
            float: left;
        }
        
        .right {
            width: 200px;
            min-height: 800px;
            background-color: lightcoral;
            float: right;
        }
    </style>
</head>

<body>
    <div class="header">header</div>
    <div class="main">
        <div class="left">left</div>
        <div class="content">content</div>
        <div class="right">right</div>
    </div>
    <div class="footer">footer</div>
</body>

</html>

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实例

实例绝对定位

实例浮动定位

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