Here is a good starting point.
HTML:
<div class="containing-table">
<div class="centre-align">
<div class="content"></div>
</div>
</div>
CSS:
.containing-table {
display: table;
width: 100%;
height: 400px; /* for demo only */
border: 1px dotted blue;
}
.centre-align {
padding: 10px;
border: 1px dashed gray;
display: table-cell;
text-align: center;
vertical-align: middle;
}
.content {
width: 50px;
height: 50px;
background-color: red;
display: inline-block;
vertical-align: top; /* Removes the extra white space below the baseline */
}
See demo at: http://jsfiddle.net/audetwebdesign/jSVyY/
.containing-table establishes the width and height context for .centre-align (the table-cell).
You can apply text-align and vertical-align to alter .centre-align as needed.
Note that .content needs to use display: inline-block if it is to be centered horizontally using the text-align property.