CSS margin-top IE/Mozilla rendering

afternoon everyone-
i’m trying to figure out why IE and Mozilla are displaying the margin-top css code differently. Mozilla properly displays a margin-top: 5px whereas IE will basically ignore it. What is strange is that IE will not bump down the image until i increase margin-top to 20 or 25px at which point Mozilla displays it much too far down in my header. any ideas on how to fix this? thanks!