That’s done differently, not with margin or padding, but an invisible border. It’s because the isotope script counts the margin as well, so it won’t work other way.
Right now it appears you added bottom margin to the elements? Instead use something like:
[code]
div.ajaxsearchpro[id*=’ajaxsearchprores’].isotopic .results .item {
border: 3px solid rgba(0, 0, 0, 0) !important;
}
[/code]
And remove the margin if you had any.