Eze camillus
" Pixel " is a static , while " percent " and " em " are relative .The size of an EM or percent depends on its parent.
generally text size of body is 16px , then it can be called as 1.00 " em" or 100%
If text size is 16 pixels, then 150% or 1.5 EM will be 24 pixels (1.5 * 16).
