前端 | 使用 css 实现居中效果方法汇总

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Appleex
发布于 2024-08-03 / 22 阅读
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前端 | 使用 css 实现居中效果方法汇总

使用 css 实现居中效果方法汇总

介绍

本章节主要汇总使用 css 实现居中效果方法(持续更新中)

使用教程

水平居中

文本对齐属性 (textAlign)

  • 条件描述
  1. 行内元素
  2. 父元素添加 text-align: center; 属性
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }       
        .child {  
            display: inline; /* 设置为行内元素,也可以直接使用行内标签 */            			border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            text-align: center;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

外边距自动适应 (margin)

  • 条件描述
  1. 块级元素
  2. 确定宽度 - 子元素宽度设置为 width: 50px;
  3. 子元素外边距设置为 margin: 0 auto;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            display: block;  
            border: 1px solid;  
            width: 50px;  
            background-color: green;  
        }        
        .next .child {  
            margin: 0 auto;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

定位与外边距 (position)

  • 条件描述
  1. 块级元素
  2. 确定元素宽度 - width: 50px;
  3. 父元素需要设置为相对定位 - position: relative;
  4. 子元素需要设置为绝对定位 - position: absolute; left: 50%;
  5. 子元素左外边距设置为该元素宽度的一半 - margin-left: -25px;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            position: relative;  
            width: 100%;  
            height: 100px;  
            border: 1px solid;  
            background-color: yellow;  
        } 
        .child {  
            display: block;  
            width: 50px;  
            height: 50px;  
            border: 1px solid;  
            background-color: green;  
        }     
        .next .child {  
            position: absolute;  
            left: 50%;  
            margin-left: -25px; /* 目标元素的宽度为 50px */ 
        }  
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

表格属性与外边距自动适应 (table)

  • 条件描述
  1. 块级元素
  2. 未知宽度 - 子元素宽度未知
  3. 子元素设置为 display: table; (或者直接使用表格标签)
  4. 子元素外边距设置为 margin: 0 auto;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next .child {  
            display: table;  
            margin: 0 auto;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

内联块状与文本对齐属性 (inlineBlock)

  • 条件描述
  1. 块级元素
  2. 未知宽度 - 子元素宽度未知
  3. 子元素设置为 display: inline-block;
  4. 父元素设置为 text-align: center;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }                
        .child {  
            border: 1px solid;  
            background-color: green;  
        }                
        .next {  
            text-align: center;  
        }                
        .next .child {  
            display: inline-block;  
        }            
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

弹性布局 (flex)

  • 条件描述
  1. 块级元素
  2. 未知宽度 - 子元素宽度未知
  3. 父元素设置为 display: flex;justify-content: center;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            display: flex;  
            justify-content: center;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

定位与移动 (css3)

  • 条件描述
  1. 块级元素
  2. 未知宽度 - 子元素宽度未知
  3. 父元素设置为相对定位 position: relative;
  4. 子元素设置为绝对定位 position: absolute;left: 50%;
  5. 子元素相对自身向左移动 tranform: translateX(-50%);
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            position: relative;  
        }        
        .next .child {  
            position: absolute;  
            left: 50%;  
            transform: translateX(-50%);  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

垂直居中

设置行高(lineHeight)

  • 条件描述
  1. 一般适用于纯文本类
  2. 子元素设置高度 height: 50px;
  3. 子元素设置行高 line-height: 50px;
  4. 子元素内的文本相对子元素垂直方向居中
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next .child {  
            height: 50px;  
            line-height: 50px;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

定位与外边距

  • 条件描述
  1. 父元素设置为相对定位 position: relative;
  2. 子元素设置为绝对定位 position: absolute; 和 方向 top: 0; bottom: 0;
  3. 子元素上下外边距设置为 margin: auto;
  4. 子元素设置宽高,否则外边距设置将无效
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            position: relative;  
        }        
        .next .child {  
            position: absolute;  
            top: 0;  
            bottom: 0;  
            margin: auto;  
            height: 50px; /* 子元素设置宽高, 否则 margin 自适应无效 */        
        }  
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

弹性布局与外边距

  • 条件描述
  1. 父元素设置为 display: flex;
  2. 子元素外边距 margin: auto 0;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            display: flex;  
        }        
        .next .child {  
            margin: auto 0;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

弹性布局 (flex)

  • 条件描述
  1. 父元素设置为 display: flex; 且垂直方向 align-items: center;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            display: flex;  
            align-items: center;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

垂直对齐属性 (verticalAlign)

  • 条件描述
  1. vertical-align 属性只能作用在 display 属性值为 inline、inline-block,inline-table 或 table-cell 的元素上
  2. vertical-align 属性设置元素的垂直对齐方式。该属性定义行内元素的基线相对于该元素所在行的基线的垂直对齐
  3. 浮动和绝对定位会让元素块状化,因此这两种情况也不会使 vertical-align 属性生效
  • 代码示例
  1. 通过 table 与 table-cell 布局实现垂直居中效果
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }       
        .next {  
            display: table;  
        }        
        .next .child {  
            display: table-cell;  
            vertical-align: middle;  
        }        
        .next .child .grandson {  
            border: 1px solid;  
            height: 50px;  
            width: 50px;  
            background-color: red;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">  
            <div class="grandson">grandson1</div>  
        </div>  
    </div>  
</body>  
</html>

table-cell 会导致宽度和高度的设置失效

  1. 嵌套三层元素,将目标元素放在 table-cell 的下一层
  2. 使用 display: table 和 display: table-row 配合使用,然后再用 display: table-cell 设置单元格。这样可以让元素遵从表格的布局原则的同时还能设置宽高。
  1. 通过两个 inline-block 内联块级元素实现其中一个目标元素垂直居中效果
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {}        
        .next .child {  
           display: inline-block;  
        }  
        .next .child:last-child {  
            visibility: hidden;  
            border: none;  
            width: 0;  
            height: inherit;  
            vertical-align: middle;  
            background-color: blue;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
        <div class="child">child2</div>  
    </div>  
</body>  
</html>

定位与位移

  • 条件描述
  1. 父元素设置为相对定位 position: relative;
  2. 子元素设置为绝对定位 position: absolute;top: 50%;
  3. 子元素相对自身向上移动 transform: translateY(-50%);
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            position: relative;  
        }        
        .next .child {  
            position: absolute;  
            top: 50%;  
            transform: translateY(-50%);  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

水平垂直居中

定位与外边距

  • 条件描述
  1. 宽高固定
  2. 父元素设置为相对定位
  3. 子元素设置为绝对定位
  • 代码示例
  1. 外边距自动适应,即:margin: auto;
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            position: relative;  
        }        
        .next .child {  
            position: absolute;  
            left: 0;  
            top: 0;  
            right: 0;  
            bottom: 0;  
  
            width: 50px;  
            height: 50px;  
  
            margin: auto;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>
  1. 外边距是宽高的一半
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            position: relative;  
        }        
        .next .child {  
            position: absolute;  
            left: 50%;  
            top: 50%;  
  
            width: 50px;  
            height: 50px;  
  
            margin-left: -25px;  
            margin-top: -25px;  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

弹性布局

  • 条件描述
  1. 父元素设置为 display: flex; justify-content: center; align-items: center;
  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            display: flex;  
            justify-content: center;  
            align-items: center;  
        }    
	</style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

定位与位移

  • 代码示例
<!DOCTYPE html>  
<html lang="en">  
<head>  
    <meta charset="UTF-8">  
    <title>Title</title>  
    <style>  
        .parent {  
            border: 1px solid;  
            width: 100%;  
            height: 100px;  
            background-color: yellow;  
        }        
        .child {  
            border: 1px solid;  
            background-color: green;  
        }        
        .next {  
            position: relative;  
        }  
        .next .child {  
            position: absolute;  
            left: 50%;  
            top: 50%;  
  
            transform: translateX(-50%) translateY(-50%);  
        }    
    </style>  
</head>  
<body>  
    <h3>测试前</h3>  
    <div class="parent pre">  
        <div class="child">child1</div>  
    </div>  
    <h3>测试后</h3>  
    <div class="parent next">  
        <div class="child">child1</div>  
    </div>  
</body>  
</html>

FAQ

参考文献


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