relative notes

this should be the easiest. it's just an offset from the normal flow position.
the quickest way to implement it is to calculate the offset and then set
x and y offsets on the box which are then used when doing the rendering

calc the offset by looking at left right and top bottom.
if neither has a number then use 0
if one has a number and the other doesnt then use the number
if both have a number and they aren't opposites, then use left / top

step 2: add the defaults of auto to the css. this means to all elements. it
doesn't inherit.

step 3: add a relative boolean to the box

the computed offset by default is 0,0
to handle the top,bottom,left,right


handle nested relatives