Margins have an easy value to input for centering regular content in HTML like divs.
in this case:
margin: 0px auto;
Provided you are using CSS, I'm positive that it is compatible with all modern browsers to my knowledge. If you are scripting in HTML then just put opening and ending <script> & </script> tags around it.
Hope this helps.
PS: I assume that you are trying to absolutely center content in your div, if you need other content to be centered as well make sure you place a proper hierarchy of order in your html for each div, or place other things in the div with proper format. Or you can use absolute positioning.