Center a DIV horizontally and vertically

For modern browsers

When you have that luxury. There's flexbox too, but that's not broadly supported at the time of this writing.

HTML:

<div class="content">This works with any content</div>

CSS:

.content {
  position: absolute;
  left: 50%;
  top: 50%;
  -webkit-transform: translate(-50%, -50%);
  transform: translate(-50%, -50%);
}

Tinker with it further on Codepen or on JSBin

For older browser support, look elsewhere in this thread.

The legitimate way to do that irrespective of size of the div for any browser size is :

   div{
    margin:auto;
    height: 200px;
    width: 200px;
    position:fixed;
    top:0;
    bottom:0;
    left:0;
    right:0;
    background:red;
   }

Live Code

After trying a lot of things I find a way that works. I share it here if it is useful to anyone. You can see it here working: http://jsbin.com/iquviq/30/edit

.content {
        width: 200px;
        height: 600px;
        background-color: blue;
        position: absolute; /*Can also be `fixed`*/
        left: 0;
        right: 0;
        top: 0;
        bottom: 0;
        margin: auto;
        /*Solves a problem in which the content is being cut when the div is smaller than its' wrapper:*/
        max-width: 100%;
        max-height: 100%;
        overflow: auto;
}

Here's a demo: http://www.w3.org/Style/Examples/007/center-example

A method (JSFiddle example)

CSS:

html, body {
    margin: 0;
    padding: 0;
    width: 100%;
    height: 100%;
    display: table
}
#content {
    display: table-cell;
    text-align: center;
    vertical-align: middle;
}

HTML:

<div id="content">
    Content goes here
</div>

Another method (JSFiddle example)

CSS

body, html, #wrapper {
    width: 100%;
    height: 100%
}
#wrapper {
    display: table
}
#main {
    display: table-cell;
    vertical-align: middle;
    text-align:center
}

HTML

<div id="wrapper">
<div id="main">
    Content goes here
</div>
</div>