This stylus mixin overrides the default CSS margin and padding properties so that you can pass size strings such as 'xl' etc

Stylus override margin and padding with default variables

margin-xs    := 0.2rem
margin-s     := 0.4rem
margin-m     := 0.6rem
margin-l     := 1rem
margin-xl    := 10rem
padding-xs   := 0.2rem
padding-s    := 0.4rem
padding-m    := 0.6rem
padding-l    := 1rem
padding-xl   := 1.5rem

getMarginValue(u)
  return typeof(u) == 'unit' || u == auto ? u : lookup('margin-' + u)
  
getPaddingValue(u)
  return typeof(u) == 'unit' ? u : lookup('padding-' + u)

/* override the margin property */ 
margin()  
  top = getMarginValue(arguments[0])
  right = bottom = left = null
  num = length(arguments)  
  if num == 4
    left = getMarginValue(arguments[3])
  if num >= 3
    bottom = getgetMarginValueMargin(arguments[2])
  if num >= 2
    right = getMarginValue(arguments[1])   
  margin top right bottom left
  
margin-top(u)
  margin-top getMarginValue(u)
  
margin-right(u)
  margin-right getMarginValue(u)
  
margin-bottom(u)
  margin-bottom getMarginValue(u)
  
margin-left(u)
  margin-left getMarginValue(u)
  
/* override the padding property */  
padding()  
  top = getPaddingValue(arguments[0])
  right = bottom = left = null
  num = length(arguments)  
  if num == 4
    left = getPaddingValue(arguments[3])
  if num >= 3
    bottom = getPaddingValue(arguments[2])
  if num >= 2
    right = getPaddingValue(arguments[1])   
  padding top right bottom left
  
padding-top(u)
  padding-top getPaddingValue(u)

padding-right(u)
  padding-right getPaddingValue(u)
  
padding-bottom(u)
  padding-bottom getPaddingValue(u)
  
padding-left(u)
  padding-left getPaddingValue(u)
  
*
  margin 'xl'
  margin auto 's'
  margin 's' auto
  margin 's' 'm' 'l' 'lx'
  margin-top 'xl'
  margin-left 'xl'
  padding 'm'
  padding 'xl' 0 'm'
  border solid 1px red
  padding-left 'xl'
  padding-bottom 'xl'