元素水平垂直居中

一、脱离文档流元素的居中

只可用于定宽高元素；

方法一：margin:auto法

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>垂直居中</title>
    <style type="text/css">
        body{
            background: #ccc;
        }
     #parent{
        border: 1px solid blue;
        height: 400px;
        width:600px;
        position: relative;
     }
     #container {
        position: absolute;
        top: 0;
        bottom: 0;
        left:0;
        right:0;
        margin: auto;
        height: 200px;
        width:300px;
        border: 1px solid red;
        /*width: 70%;*/
    }
</style>
</head>

<body>
    <div id="parent">
        <div id="container">
        <p>我要用绝对定位水平垂直居中</p>
        <p>我要用绝对定位水平垂直居中</p>
        <p>我要用绝对定位水平垂直居中</p>
    </div>
    </div>
    
</body>
</html>

方法二：负margin法

父元素设置为：position: relative; 
子元素设置为：position: absolute;

距上50%，据左50%，然后减去元素自身宽度的距离就可以实现 top:50%;left:50%;margin:-height/2 0 0 -width/2;

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>定宽块状元素水平居中</title>
<style>
body{
    background: #ccc;
}
div{
    position: relative;
    height: 400px;
    width:400px;
    border:1px solid blue;
}
p{
    position: absolute;
    top: 50%;
    left:50%;
    height: 200px;
    width:200px;
    margin: -100px 0  0 -100px; 
    border:1px solid red;

}

</style>
</head>

<body>
<div><p>我是定宽块状元素，我要垂直水平居中显示。</p></div>
</body>
</html>

方法三：transform 

定宽高和不定宽高元素皆可；

用法：

#child {
        position: absolute;
        top: 50%;
        left:50%;
        transform: translate(-50%,-50%);
      /*  height: 200px;
        width:300px;*/
        border: 1px solid red;
    }
<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>垂直居中</title>
    <style type="text/css">
        body{
            background: #ccc;
        }
     #parent{
        border: 1px solid blue;
        height: 400px;
        width:600px;
        position: relative;
     }
     #container {
        position: absolute;
        top: 50%;
        left:50%;
        transform: translate(-50%,-50%);
      /*  height: 200px;
        width:300px;*/
        border: 1px solid red;
    }
</style>
</head>

<body>
    <div id="parent">
        <div id="container">
        <p>我要用绝对定位水平垂直居中</p>
        <p>我要用绝对定位水平垂直居中</p>
        <p>我要用绝对定位水平垂直居中</p>
    </div>
    </div>
    
</body>
</html>

二、未脱离文档流元素的居中

方法一：table-cell法

有一定的bug,父元素会和子元素一般大，但是确实居中了；

定宽高和不定宽高元素皆可；

<!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>垂直居中</title>
    <style type="text/css">
    body{
        background:#ccc;
    }

        #wrapper {
            display: table;    /*here*/
            border:1px solid yellow;
        }
        
        #container {
            display: table-cell;       /*here*/       
            vertical-align: middle;    /*here*/
            text-align: center;
  
            height:200px;
            width:300px;
            border:1px solid red;
        }
    </style>
</head>
<body>
    <div id="wrapper">
        <div id="container">
            <p>我要用表格属性垂直水平居中</p>
            <p>我要用表格属性垂直水平居中</p>
            <p>我要用表格属性垂直水平居中</p>
        </div> 
    </div> 
</body>
</html>

方法二：flex布局

定宽高和不定宽高元素皆可；

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>定宽块状元素水平居中</title>
<style>
body{
    background: #ccc;
}
div{
 
    height: 400px;
    width:400px;
    border:1px solid red;
    display:flex;
    justify-content: center;
    align-items: center;
}
p{
    height:100px;
    width:100px;
    border:1px solid blue;
}
</style>
</head>

<body>
<div><p>我是定宽块状元素，我要垂直水平居中显示。</p></div>
</body>
</html>

 

posted @ 2018-08-03 12:00  sunmarvell  阅读(266)  评论(0)  编辑  收藏  举报