Best way to center a <div> on a page vertically and horizontally? [duplicate]

Question

The best and most flexible way

The main trick in this demo is that in the normal flow of elements going from top to bottom, so the margin-top: auto is set to zero. However, an absolutely positioned element acts the same for distribution of free space, and similarly can be centered vertically at the specified top and bottom (does not work in IE7).

##This trick will work with any sizes of div.

div {
    width: 100px;
    height: 100px;
    background-color: red;
    
    position: absolute;
    top:0;
    bottom: 0;
    left: 0;
    right: 0;
    
    margin: auto;
}

<div></div>

Even though this did not work when the OP asked this question, I think, for modern browsers at least, the best solution is to use display: flex or pseudo classes.

You can see an example in the following fiddle. Here is the updated fiddle.

For pseudo classes an example could be:

.centerPseudo {
    display:inline-block;
    text-align:center;
}

.centerPseudo::before{
    content:'';
    display:inline-block;
    height:100%;
    vertical-align:middle;
    width:0px;
}

The usage of display: flex, according to css-tricks and MDN is as follows:

.centerFlex {
  align-items: center;
  display: flex;
  justify-content: center;
}

There are other attributes available for flex, which are explained in above mentioned links, with further examples.

If you have to support older browsers, which don't support css3, then you should probably use javascript or the fixed width/height solution shown in the other answers.

Simplicity of this technique is stunning:
(This method has its implications though, but if you only need to center element regardless of flow of the rest of the content, it's just fine. Use with care)

Markup:

<div>Lorem ipsum dolor sit amet, consectetur adipiscing elit. Vestibulum accumsan tellus purus, et mollis nulla consectetur ac. Quisque id elit at diam convallis venenatis eget sed justo. Nunc egestas enim mauris, sit amet tempor risus ultricies in. Sed dignissim magna erat, vel laoreet tortor bibendum vitae. Ut porttitor tincidunt est imperdiet vestibulum. Vivamus id nibh tellus. Integer massa orci, gravida non imperdiet sed, consectetur ac quam. Nunc dignissim felis id tortor tincidunt, a eleifend nulla molestie. Phasellus eleifend leo purus, vel facilisis massa dignissim vitae. Pellentesque libero sapien, tincidunt ut lorem non, porta accumsan risus. Morbi tempus pharetra ex, vel luctus turpis tempus eu. Integer vitae sagittis massa, id gravida erat. Maecenas sed purus et magna tincidunt faucibus nec eget erat. Lorem ipsum dolor sit amet, consectetur adipiscing elit. Nunc nec mollis sem.</div>

And CSS:

div {
  color: white;
  background: red;
  padding: 15px;
  position: absolute;
  top: 50%;
  left: 50%;
  -ms-transform: translateX(-50%) translateY(-50%);
  -webkit-transform: translate(-50%,-50%);
  transform: translate(-50%,-50%);
}   

This will center element horizontally and vertically too. No negative margins, just power of transforms. Also we should already forget about IE8 shouldn't we?

I would use translate:

First position the div's top left corner at the center of the page (using position: fixed; top: 50%; left: 50%). Then, translate moves it up by 50% of the div's height to center it vertically on the page. Finally, translate also moves the div to the right by 50% of it's width to center it horizontally.

I actually think that this method is better than many of the others, since it does not require any changes on the parent element.

translate is better than translate3d in some scenarios due to it being supported by a greater number of browsers. https://caniuse.com/#feat=transforms2d

To sum it up, this method is supported on all versions of Chrome, Firefox 3.5+, Opera 11.5+, all versions of Safari, IE 9+, and Edge.

.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>

Notice, however, that this method makes this div stay in one place while the page is being scrolled. This may be what you want but if not, there is another method.

Now, if we try the same CSS, but with position set to absolute, it will be in the center of the last parent that has an absolute position.

.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>