Hi, you set pixel widths (104.5px) however a half pixel doesn't exist (think about it, why would it )
Some browsers round that up, some down. As a result you will have a few pixels difference.
Assign a standard width (no half pixels) and all should be good.
Though to get it perfectly lininig up, some will need to have a diferent width set (aka standardly set 105px..some might need 104px or 106px to get it perfect)