CSS block horizontal and vertical centering personal summary

1. Use inline-block and vertical-align to achieve centering: This method is suitable for unknown width and height.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #container{
            text-align: center;
            height: 400px;
            background: #4dc71f;
        }
        #container:before{
            content: "";
            height: 100%;
            display: inline-block;
            vertical-align: middle;
            margin-right: -0.25em;
        }
        #center-div{
            display: inline-block;
            vertical-align: middle;
            background: #2aabd2;

        }
    </style>
</head>
<body>
    <div id="container">
        <div id="center-div">
            xxx
        </div>
    </div>
</body>

2. Use absolute positioning to achieve centering: suitable for situations where the height and width are known.

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #container{
            text-align: center;
            height: 400px;
            background: #4dc71f;
            position: relative;
        }
        #center-div{
            position: absolute;
            margin: auto;
            top: 0;
            right: 0;
            left:0;
            bottom: 0;
            width: 200px;
            height: 200px;
            background: #2b669a;
        }
    </style>
</head>
<body>
    <div id="container">
        <div id="center-div">
            xxx
        </div>
    </div>
</body>
</html>

3. Use table-cell, inline-block to achieve horizontal and vertical centering: suitable for unknown height and width

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #container{
            display: table-cell;
            text-align: center;
            vertical-align: middle;
            height: 300px;
            width: 300px;
            background: #ccc;
        }
        #center-div{
            display: inline-block;
        }
    </style>
</head>
<body>
    <div id="container">
        <div id="center-div">
            xxx
        </div>
    </div>
</body>
</html>

4. Element solution with unknown height and width transform: translate(-50%, -50%);

<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
    #container{
        position: relative;
        width: 500px;
        height: 500px;
    }
    #center-div{
        position: absolute;
        top: 50%;
        left: 50%;
        transform: translate(-50%, -50%);  /* 使用css3的transform来实现 */
    }
    </style>
</head>
<body>
    <div id="container">
        <div id="center-div">
            xxx
        </div>
    </div>
</body>
</html>

5.Flexbox to achieve horizontal and vertical centering; suitable for unknown width and height, but pay attention to compatibility

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        #p_2{
            display: flex;
            justify-content: center;
            align-items: center;
            width: 200px;
            height: 200px;
            background: #009f95;
        }
    </style>
</head>
<body>
    <div id="p_2">
        <div id="c_2">
            xxxxxxx
        </div>
    </div>
</body>
</html>

CSS block horizontal and vertical centering personal summary

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