Cleaning up CSS styles

[nimbupani]

• Noticed there were 4 references like: margin-top: x; margin-left: y; margin-bottom: x; margin-right: y; changed that to: margin: x y;
• There were only -webkit- prefixed properties, in the very near future, the prefixes will be dropped (Chrome already has for both radius and shadow), so I added the unprefixed versions.
• footnotes li p:first-child:before had margin-left: 0px for some reason, which seemed to make no difference.