lovecoding
/
W250913


			
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							<!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>
        .box1{
            width: 400px;
            height: 400px;
            background-color: blue;
            /* float: left; */
            overflow: hidden;
            /* display: inline-block */
            /* border:1px solid black; */
        }
        .box2{
            width: 200px;
            height: 200px;
            background-color: red;
            margin-top: 100px;
            margin-left: 100px;
        }
        .box3,.box4{
            width: 200px;
            height: 200px;
        }
        .box3{
            background-color: green;
            margin-bottom: 20px;
        }
        .box4{
            margin-top: 30px;
            background-color: yellow;
        }
        .box5{
            overflow: hidden;
        }
    </style>
</head>
<body>
    <!-- 外边距溢出  仅限于垂直方向 margin-top-->
    <!-- BFC 块格式化上下文-->
    <!-- BFC 限制内部元素与外部元素接触 内部元素所有效果仅限于BFC区域内 -->


    <div class="box1">
        <div class="box2"></div>
    </div>


    <!-- 外边距合并 上下两个相邻元素  垂直方向 margin-top margin-bottom 合并成一个 -->
    <div class="box5">
        <div class="box3"></div>
    </div>
    <div class="box4"></div>
</body>
</html>