How to vertically center a "div" element for all browsers using CSS?

Below is the best all-around solution I could build to vertically and horizontally center a fixed-width, flexible height content box. It was tested and working for recent versions of Firefox, Opera, Chrome, and Safari.

.outer {
  display: table;
  position: absolute;
  top: 0;
  left: 0;
  height: 100%;
  width: 100%;
}

.middle {
  display: table-cell;
  vertical-align: middle;
}

.inner {
  margin-left: auto;
  margin-right: auto;
  width: 400px;
  /*whatever width you want*/
}

<div class="outer">
  <div class="middle">
    <div class="inner">
      <h1>The Content</h1>
      <p>Once upon a midnight dreary...</p>
    </div>
  </div>
</div>

View A Working Example With Dynamic Content

I built in some dynamic content to test the flexibility and would love to know if anyone sees any problems with it. It should work well for centered overlays also -- lightbox, pop-up, etc.

One more I can't see on the list:

.Center-Container {
  position: relative;
  height: 100%;
}

.Absolute-Center {
  width: 50%;
  height: 50%;
  overflow: auto;
  margin: auto;
  position: absolute;
  top: 0; left: 0; bottom: 0; right: 0;
  border: solid black;
}

• Cross-browser (including Internet Explorer 8 - Internet Explorer 10 without hacks!)
• Responsive with percentages and min-/max-
• Centered regardless of padding (without box-sizing!)
• height must be declared (see Variable Height)
• Recommended setting overflow: auto to prevent content spillover (see Overflow)

_{Source: Absolute Horizontal And Vertical Centering In CSS}

The simplest way would be the following 3 lines of CSS:

1) position: relative;

2) top: 50%;

3) transform: translateY(-50%);

Following is an EXAMPLE:

div.outer-div {
  height: 170px;
  width: 300px;
  background-color: lightgray;
}

div.middle-div {
  position: relative;
  top: 50%;
  -webkit-transform: translateY(-50%);
  -ms-transform: translateY(-50%);
  transform: translateY(-50%);
}

<div class='outer-div'>
  <div class='middle-div'>
    Test text
  </div>
</div>