أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
there is another unit, pt (point). It is little bit larger than px, i.e.12pt >12px
em is universal and it looks good in pc & mac. At the same time it looks good though you zoom in & out in your screen. Where its completely opp to px.