关于width的继承和获取

absolute元素（如果没有设置width值），其宽度自适应于内部元素，

<!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>
        body,
        html {
            margin: 0;
            padding: 0
        }
        
        .div1 {
            width: 100%;
            height: 300px;
            background: red
        }
        
        .div2 {
            background: blue;
            height: 200px;
            position: absolute;
        }
        
        .div3 {
            width: 100px;
            background: yellow;
            height: 50px;
        }
    </style>
</head>

<body>
    <div class="div1">
        <div class="div2">
            <div class="div3"></div>
        </div>
    </div>
</body>

</html>

 





<!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>
        body,
        html {
            margin: 0;
            padding: 0
        }
        
        .div1 {
            /* width: 100%; */
            height: 300px;
            background: red
        }
        
        .div2 {
            background: blue;
            height: 200px
        }
        
        .div3 {
            width: 100px;
            background: yellow;
            height: 50px;
        }
    </style>
</head>

<body>
    <div class="div1">
        <div class="div2">
            <div class="div3"></div>
        </div>
    </div>
</body>

</html>






如果最外层div 不给宽度，内层div不设置宽度，则宽度均为100%；




 








 






            

            
posted @ 
2017-09-11 18:06 
莫笑我胡为 
阅读(139) 
评论(0) 
编辑 
收藏 
举报