According to Box Model:
- If there is only one value, it applies
to all sides.- If there are two values,
the top and bottom margins are set to
the first value and the right and left
margins are set to the second.- If
there are three values, the top is set
to the first value, the left and right
are set to the second, and the bottom
is set to the third.- If there are four
values, they apply to the top, right,
bottom, and left, respectively.
body { margin: 2em } /* all margins set to 2em */
body { margin: 1em 2em } /* top & bottom = 1em, right & left = 2em */
body { margin: 1em 2em 3em } /* top=1em, right=2em, bottom=3em, left=2em */
This is defined by the CSS standard, so it should be consistent across all browsers that implements CSS correctly. For browser compatibilities, check out blooberry’s CSS Support History and quirksmode. According to blooberry, margin was first implemented in IE3, so IE6 should be fine.