I've borrowed a Chicco Next2Me crib from my cousin and she loved it. The only thing I'm worried about is the height of my mattress. We've got a kingsize divan bed, and the straps fit round the mattress nicely so the crib can be kept in place ok, but our mattress is quite deep. The instructions say there should be a maximum of 2cm from the top of our mattress to the top of the drop down side of the crib, but there's more like 5 or 6cm difference with ours. Do you think this will be a problem? Would it actually make it unsafe?