margin and aspectRatio convention options

[1wheel]

aspectRatio: set height equal to width/aspectRatio

margin: 0 equivalent to margin: {top: 0, left: 0, bottom: 0, right: 0}

[1wheel]

Not sure if these are better, I just don't like writing out the whole object...

margin: {t: 5, r: 10, b: 15, l: 20}

margin: [5, 10, 15, 20]