CSS marginsEdit
- Why you should try to stick to "single-direction" margins: http://csswizardry.com/2012/06/single-direction-margin-declarations/
The article recommends always favoring margin-top/margin-left, but margin-bottom/margin-right works just as well.
- On margin collapsing: https://developer.mozilla.org/en-US/docs/CSS/margin_collapsing