使用Flex-box在我看来:

#{母公司 显示:flex; justify-content:中心; 对齐项目:中心; ｝ < div id = "父" > <div id="child">Hello World!< / div > < / div >

您可以看到，只有三个CSS属性可以用于将子元素垂直和水平居中。显示:flex;通过激活Flex-box display来完成主要部分，justify-content: center;将子元素垂直居中并对齐-items: Center;水平居中。为了看到最好的结果，我只添加了一些额外的样式:

#{母公司 显示:flex; justify-content:中心; 对齐项目:中心; 身高:500 px; 宽度:500 px; 背景:黄色; ｝ #孩子{ 宽度:100 px; 身高:100 px; 背景:银色; ｝ < div id = "父" > <div id="child">Hello World!< / div > < / div >

如果你想了解更多关于Flex-box的知识，你可以访问W3Schools, MDN或CSS-Tricks获取更多信息。

如果你正在使用JQuery，你可以使用.position();

<div class="positionthis"></div>

CSS

.positionthis {
    width:100px;
    height:100px;
    position: absolute;
    background:blue;
}

Javascript JQuery ()

$(document).ready(function () {
    $('.positionthis').position({
        of: $(document),
        my: 'center center',
        at: 'center center',
        collision: 'flip flip'
    });
});

http://jsfiddle.net/vx9gV/

利用Flex显示的简单解决方案

 <div style = 'display:flex; position:absolute; top:0; bottom:0; right:0; left:0; '>
      <div id = 'div_you_want_centered' style = 'margin:auto;'> 
           This will be Centered 
      </div>
 </div>

查看http://css-tricks.com/snippets/css/a-guide-to-flexbox/

第一个div占据了整个屏幕，并有一个针对每种浏览器的显示:flex集。第二个div(居中div)充分利用了显示:flex div，其中margin:auto工作出色。

注意兼容IE11+。(IE10 w/ prefix)。

我会使用translate:

首先，将div的左上角定位在页面的中心(使用位置:固定;上图:50%;左:50%)。然后，translate将其向上移动50%的div高度，使其在页面上垂直居中。最后，translate还将div向右移动50%的宽度，使其水平居中。

实际上，我认为这个方法比其他许多方法更好，因为它不需要对父元素进行任何更改。

在某些情况下，Translate比translate3d更好，因为它被更多的浏览器支持。https://caniuse.com/#feat=transforms2d

综上所述，所有版本的Chrome、Firefox 3.5+、Opera 11.5+、所有版本的Safari、IE 9+和Edge都支持此方法。

.centered { position: fixed; top: 50%; left: 50%; transform: translate(-50%, -50%); -webkit-transform: translate(-50%, -50%); -moz-transform: translate(-50%, -50%); -o-transform: translate(-50%, -50%); -ms-transform: translate(-50%, -50%); font-size: 20px; background-color: cyan; border: darkgreen 5px solid; padding: 5px; z-index: 100; } table { position: absolute; top: 0; left: 0; } td { position: relative; top: 0; left: 0; } <table> <tr> <td> <div class="centered">This div<br />is centered</div> <p> Lorem ipsum dolor sit amet, nam sint laoreet at, his ne sumo causae, simul decore deterruisset ne mel. Exerci atomorum est ut. At choro vituperatoribus usu. Dico epicurei persequeris quo ex, ea ius zril phaedrum eloquentiam, duo in aperiam admodum fuisset. No quidam consequuntur usu, in amet hinc simul eos. Ex soleat meliore percipitur mea, nihil omittam salutandi ut eos. Mea et impedit facilisi pertinax, ea viris graeci fierent pri, te sonet intellegebat his. Vis denique albucius instructior ad, ex eum iudicabit elaboraret. Sit ea intellegam liberavisse. Nusquam quaestio maiestatis ut qui, eam decore altera te. Unum cibo aliquip ut qui, te mea doming prompta. Ex rebum interesset nam, te nam zril suscipit, qui suavitate explicari appellantur te. Usu brute corpora mandamus eu. Dicit soluta his eu. In sint consequat sed, quo ea tota petentium. Adhuc prompta splendide mel ad, soluta delenit nec cu. </p> </td> <td> <p> Lorem ipsum dolor sit amet, dico choro recteque te cum, ex omnesque consectetuer sed, alii esse utinam et has. An qualisque democritum usu. Ea has habeo labores, laoreet intellegat te mea. Eius equidem inermis vel ne. Ne eum sonet labitur, nec id natum munere. Primis graecis est cu, quis dictas eu mea, eu quem offendit forensibus nec. Id animal mandamus his, vis in sonet tempor luptatum. Ne civibus oporteat comprehensam vix, per facete discere atomorum eu. Mucius probatus volutpat sit an, sumo nominavi democritum eam ut. Ea sit choro graece debitis, per ex verear voluptua epicurei. Id eum wisi dicat, ea sit velit doming cotidieque, eu sea amet delenit. Populo tacimates dissentiunt has cu. Has wisi hendrerit at, et quo doming putent docendi. Ea nibh vide omnium usu. </p> </td> </tr> </table>

但是，请注意，该方法使该div在页面滚动时停留在一个位置。这可能是你想要的，但如果不是，还有另一种方法。

现在，如果我们尝试相同的CSS，但将位置设置为绝对，它将在最后一个具有绝对位置的父元素的中心。

.centered { position: absolute; top: 50%; left: 50%; transform: translate(-50%, -50%); -webkit-transform: translate(-50%, -50%); -moz-transform: translate(-50%, -50%); -o-transform: translate(-50%, -50%); -ms-transform: translate(-50%, -50%); font-size: 20px; background-color: cyan; border: darkgreen 5px solid; padding: 5px; z-index: 100; } table { position: absolute; top: 0; left: 0; } td { position: relative; top: 0; left: 0; } <table> <tr> <td> <div class="centered">This div<br />is centered</div> <p> Lorem ipsum dolor sit amet, nam sint laoreet at, his ne sumo causae, simul decore deterruisset ne mel. Exerci atomorum est ut. At choro vituperatoribus usu. Dico epicurei persequeris quo ex, ea ius zril phaedrum eloquentiam, duo in aperiam admodum fuisset. No quidam consequuntur usu, in amet hinc simul eos. Ex soleat meliore percipitur mea, nihil omittam salutandi ut eos. Mea et impedit facilisi pertinax, ea viris graeci fierent pri, te sonet intellegebat his. Vis denique albucius instructior ad, ex eum iudicabit elaboraret. Sit ea intellegam liberavisse. Nusquam quaestio maiestatis ut qui, eam decore altera te. Unum cibo aliquip ut qui, te mea doming prompta. Ex rebum interesset nam, te nam zril suscipit, qui suavitate explicari appellantur te. Usu brute corpora mandamus eu. Dicit soluta his eu. In sint consequat sed, quo ea tota petentium. Adhuc prompta splendide mel ad, soluta delenit nec cu. </p> </td> <td> <p> Lorem ipsum dolor sit amet, dico choro recteque te cum, ex omnesque consectetuer sed, alii esse utinam et has. An qualisque democritum usu. Ea has habeo labores, laoreet intellegat te mea. Eius equidem inermis vel ne. Ne eum sonet labitur, nec id natum munere. Primis graecis est cu, quis dictas eu mea, eu quem offendit forensibus nec. Id animal mandamus his, vis in sonet tempor luptatum. Ne civibus oporteat comprehensam vix, per facete discere atomorum eu. Mucius probatus volutpat sit an, sumo nominavi democritum eam ut. Ea sit choro graece debitis, per ex verear voluptua epicurei. Id eum wisi dicat, ea sit velit doming cotidieque, eu sea amet delenit. Populo tacimates dissentiunt has cu. Has wisi hendrerit at, et quo doming putent docendi. Ea nibh vide omnium usu. </p> </td> </tr> </table>

虽然我太晚了，但这很简单。页面中心总是向左50%，顶部50%。减去div width和height的50%设置左右边距。希望它适用于所有地方

身体{ 背景:# EEE; ｝ .center-div { 位置:绝对的; 宽度:200 px; 高度:60 px; 左:50%; margin-left: -100 px; 上图:50%; margin-top: -30 px; 背景:# CCC; 颜色:# 000; text-align:中心; ｝ < div class = " center-div”> <h3>这是中心div</h3> < / div >

position: absolute;
left: 50%;
top: 50%;
-webkit-transform: translate(-50%, -50%);
-ms-transform: translate(-50%, -50%);
transform: translate(-50%, -50%);

解释:

给它一个绝对定位(父元素应该有相对定位)。然后，左上角被移动到中心。因为你还不知道宽度/高度，所以你使用css transform来转换相对于中间的位置。平移(-50%，-50%)会将左上角的x和y位置降低50%的宽度和高度。