In IE7-, only on body, background position in em unit does not take into account a font-size declaration. Here html has font-size: 5em. Html and an inner div have both a square background image not repeated, positioned at 1em 1em. The two overlap (the html's one is red and bigger), there is no problem since this only occurs on body. To see the problem: IE7-: em background-position and font-size on body.