CSS布局技巧：无需知道元素宽高的居中方法-优快云博客

1. CSS3.0弹性布局flex, 无需知道父子元素宽高

<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <title>弹性布局flex, 无需知道父子元素宽高</title>
    <style>
    html,
    body {
        width: 100%;
        height: 100%;
        margin: 0;
        padding: 0;
    }

    body {
        display: flex;
        align-items: center;
        /*定义body的子元素垂直居中*/
        justify-content: center;
        /*定义body的子元素水平居中*/
    }

    .content {
        width: 300px;
        height: 300px;
        background: orange;
    }
    </style>
</head>

<body>
    <div class="content"></div>
</body>

</html>

2. vertical-align:middle垂直居中, text-align: center水平居中, 无需知道父子元素宽高

<!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>vertical-align:middle垂直居中, text-align: center水平居中, 无需知道父子元素宽高</title>
    <style>
    .big-box {
        width: 500px;
        height: 400px;
        background: green;
        text-align: center;
    }

    .box {
        line-height: 400px;
    }

    img {
        vertical-align: middle;
    }
    </style>
</head>

<body>
    <div class="big-box">
        <span class="box">
            <img src="ermao.jpg" />
        </span>
    </div>
</body>

</html>

3. position: absolute加margin: auto, 无需知道父子元素宽高

<!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>position: absolute加margin: auto, 无需知道父子元素宽高</title>
    <style>
    .center-vertical {
        width: 100px;
        height: 100px;
        background: orange;
        margin: auto;
        /* 一般margin: auto只能实现水平居中, 垂直方向设置无效;
            设置以下5行样式和设置元素高度, 会有一种特殊场景, margin: auto会垂直居中。
        */
        position: absolute;
        top: 0;
        left: 0;
        right: 0;
        bottom: 0;
    }
    </style>
</head>

<body>
    <div class="center-vertical"></div>
</body>

</html>

4. position: absolute加transform: translate( -50%, -50%), 无需知道父子元素宽高

<!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>position: absolute加transform: translate( -50%, -50%), 无需知道父子元素宽高</title>
    <style>
    .content{
        background: orange;
        position: absolute;
        top: 50%;
        left: 50%;
        /* transform: translate( -50%, -50%)是根据自身元素的宽高的百分比 */
        /* 这里不能用margin-top: -50%; margin-left: -50%; 因为不论margin水平方向还是垂直方向的百分比, 都是根据父元素的宽的百分比 */
        transform: translate( -50%, -50%);
    }
    </style>
</head>
<body>
    <div class="content">你复合1233肥反反复复</div>
</body>
</html>

5. position: relative加transform: translateY(-50%)实现垂直居中, margin: 0 auto实现水平居中, 无需知道父子元素宽高

<!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>position: relative加transform: translateY(-50%)实现垂直居中, margin: 0 auto实现水平居中, 无需知道父子元素宽高</title>
    <style>
    html,body{
        width: 100%;
        height: 100%;
        margin: 0;
        padding: 0;
    }
    .content{
        width: 300px;
        height: 300px;
        background: orange;
        margin: 0 auto;/*水平居中*/
        position: relative;/*设置position*/
        top: 50%; /*偏移*/
        transform: translateY(-50%);
    }
    </style>
</head>
<body>
    <div class="content"></div>
</body>
</html>

6. display:table实现

<!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>display: table-cell;</title>
    <style>
    .parent{
        width: 300px;
        height: 300px;
        background: orange;
        text-align: center;
        display: table;
    }
    .son{
        display: table-cell;
        background-color: yellow;
        vertical-align: middle;
    }
    </style>
</head>
<body>
    <div class="parent">
        <div class="son">nihaosssss</div>
    </div>
</body>
</html>

CSS实现水平垂直居中