1em vs 10px
This should appear as 10px, set using em's
This should appear as 10px, although set implicitly

1.5em vs 15px
This should appear as 15px, set using em's
This should appear as 15px, although set implicitly

2.2em vs 22px
This should appear as 22px, set using em's
This should appear as 22px, although set implicitly