The Zombie: Leaving off units
Always a Zombie? No (some things shouldn’t have units)
Severity: medium-high
Why is it a zombie: It can prevent the property from working
Cure the Zombie by: Add units to all dimensions unless they are 0 or you are using line-height. Line-height is at its most robust and flexible when used as a multiplier. A unit-less number is ideal for line-height.