Need smaller row height (IE works, Chrome/Firefox do not)

I am trying to use a smaller row height using the following code:

div.gridbox.gridbox_dhx_skyblue table.row20px.obj tr td {
font-size: 11px;
height:18px !important;
}

The above code works for IE, but neither Chrome or Firefox seem to allow the row height to go below about 23px. Anything else I can try? I need to get a few more rows on my grid and 5 px/row makes a big difference for this application.

Thank you.

You may create a custom skin with the required row height using the skin builder.
dhtmlx.com/docs/products/skinBuilder/

Thanks for the reply. Custom skin builder is definitely an option I may explore. For now, I am using:

div.gridbox.gridbox_dhx_skyblue table.row20px.obj tr td {
height: 18px;
line-height:0px;
padding-top: 0 !important;
padding-bottom: 0 !important;
}

which accomplishes what I need for now in IE, Chrome and Firefox. line-height:0px did the trick for me and reducing the padding helped as well.