datatable margin between rows

Webix JS
#1

i need to style my datatable the following way: white rows on grey background with no borders and 2px margin between rows. If in css i set

.webix_cell {
    margin-bottom: 2px;
    background-color: #FFF !important;
}

then i have datatable height bigger then layout and last rows become invisible as (i think so) table height is counted depending on rows height and doesn’t include my css margins. How can I fix this?

#2

https://webix.com/snippet/1102948e

#3

well, the thing is that i cannot set rowHeight
it is treetable
parent rows have height 60, children rows have height 30

scheme: {
	$init:function(obj){
		if (obj.id_parent) {
			obj.$height = 30;
			obj.$css    = 'catalog_subrow';
		} else {
			obj.$height     = 60;
			obj.$css        = 'catalog_row';
		}
	},
}
#4

then you need to create styles for parent and child rows separately