margin重疊現象

 

1.上下/左右相鄰的普通元素margin,不是二者相加之和,而是取最大值,這個現象叫作margin重疊。 
2. 普通元素纔會發生margin重疊,若是是float元素,就不會發生。margin是二者相加之和。html

例如:1普通元素spa

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>練習(margin重疊現象)</title>
    <style>
                  #test1{
                      height: 100px;
                      background: blue;
                      margin-bottom: 50px;
                  }
                  #test2{
                      height: 100px;
                      background: green;
                      margin-top:50px; 
                  }
    </style>
</head>
<body>
    <div id="test1"></div>
    
    <div id="test2"></div>
</body>
</html>

2,浮動元素:code

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>練習(margin重疊現象)</title>
    <style>
                  #test1{
                      height: 100px;
                    width: 200px;
                      background: blue;
                    margin-bottom: 50px;
                    float: left;
                  }
                  #test2{
                      height: 100px;
                    width: 200px;
                      background: green;
                       float: left;
                     clear: left;
                      margin-top:50px; 
                  }
    </style>
</head>
<body>
    <div id="test1"></div>
        <div id="test2"></div>
    
</body>
</html>

3,父子(普通元素)發生margin重疊現象htm

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>練習(margin重疊現象)</title>
    <style>
                  #test1{
                      height: 150px;
                    width: 200px;
                      background: blue;

                   
                  }
                  #test2{
                      height: 50px;
                    width: 50px;
                      background: green;
                      
                      margin-bottom:50px; 
                  }
                  #test3{
                    height: 50px;
                    width: 50px;
                    background: green;
                    margin-top: 50px;
                  }
    </style>
</head>
<body>
    <div id="test1">
        <div id="test2"></div>
        <div id="test3"></div>
    </div>
</body>
</html>

4,父子(子爲浮動元素)不發生margin重疊blog

 

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>練習(margin重疊現象)</title>
    <style>
                  #test1{
                      height: 150px;
                    width: 200px;
                      background: blue;

                   
                  }
                  #test2{
                      height: 50px;
                    width: 50px;
                      background: green;
                      float: left;
                      margin-bottom:50px; 
                  }
                  #test3{
                    height: 50px;
                    width: 50px;
                    background: green;
                    float: left;
                    clear: left;
                    margin-top: 50px;
                  }
    </style>
</head>
<body>
    <div id="test1">
        <div id="test2"></div>
        <div id="test3"></div>
    </div>
</body>
</html>

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