Align contents inside a div

text-align aligns text and other inline content. It doesn't align block element children.

To do that, you want to give the element you want aligned a width, with ‘auto’ left and right margins. This is the standards-compliant way that works everywhere except IE5.x.

<div style="width: 50%; margin: 0 auto;">Hello</div>

For this to work in IE6, you need to make sure Standards Mode is on by using a suitable DOCTYPE.

If you really need to support IE5/Quirks Mode, which these days you shouldn't really, it is possible to combine the two different approaches to centering:

<div style="text-align: center">
    <div style="width: 50%; margin: 0 auto; text-align: left">Hello</div>
</div>

(Obviously, styles are best put inside a stylesheet, but the inline version is illustrative.)

<div class="content">Hello</div>

.content {
    margin-top:auto;
    margin-bottom:auto;
    text-align:center;
}

Below are the methods which have always worked for me

1. By using flex layout model:

Set the display of the parent div to display: flex; and the you can align the child elements inside the div using the justify-content: center; (to align the items on main axis) and align-items: center; (to align the items on cross axis).

If you have more than one child element and want to control the way they are arranged (column/rows), then you can also add flex-direction property.

Working example:

.parent {
  align-items: center;
  border: 1px solid black;
  display: flex;
  justify-content: center;
  height: 250px;
  width: 250px;
}

.child {
  border: 1px solid black;
  height: 50px;
  width: 50px;
}

<div class="parent">
  <div class="child"></div>
</div>

2. (older method) Using position, margin properties and fixed size

Working example:

.parent {
  border: 1px solid black;
  height: 250px;
  position: relative;
  width: 250px;
}

.child {
  border: 1px solid black;
  margin: auto;
  top: 0;
  bottom: 0;
  left: 0;
  right: 0;
  height: 50px;
  position: absolute;
  width: 50px;
}

<div class="parent">
  <div class="child"></div>
</div>