there is a alternative to margin-left:auto; margin-right: auto;
or margin:0 auto;
for the ones that use position:absolute;
this is how:
you set the left position of the element to 50% (left:50%;
) but that will not center it correctly in order for the element to be centered correctly you need to give it a margin of minus half of it`s width, that will center your element perfectly
here is an example: http://jsfiddle.net/35ERq/3/