2 EM for font size = x * 2 PARENTS font size
2 REM for font size = x * 2 ROOT font size
!if EM is used to specify length, than width: 2em = current elements font size * 2!
INHERITENCE:
.parent {
font-size: 20px;
line-height: 150%;
}
.child {
font-size: 30px;
}
here, child's line-height will be 20px*150% = 30px;
IT INHERITS COMPUTED VALUE OF 30PX, NOT 150%