As of WithStyle V4 version 4.875 we now have proper margin: auto behaviour for regular blocks. This means that you can actually center a block in the middle of a window area using just the single style 'margin: auto'. If you give it a fixed width and height, you should see the blocks content in the middle of the screen.

There is one caveat to this. If your content overflows the margin: auto'd block, then the margin-top and margin-bottom will collapse down to 0 pixels. And this is where other rendering technologies come unstuck. Below are pictures of IE7, Firefox and WithStyle rendering the same document using margin: auto; width: 400px; height: 200px. Firefox comes the closest but assumes there is overflow and therefore collapses the top/bottom. IE6 and IE7b2 just stick the block in the top/left corner as if it had no margin what so ever.

Speaking of IE7b2, if you go to www.w3.org and try to hover over the section links, to our surprise we found that it did not honor the hover styles and change the links to be red with a yellow background! Wow.. talk about a regression.

WithStyle V4:

IE7:

Firefox: