XF 1.5 I need that gap

Hi Folks, just wondering if anyone can help. On my previous forums (Vb3) I had a small gap between individual posts when viewing a thread (see screen grab). Is there any way to replicate this in XF 1.5? I've squinted and strained over the huge array of customisable items but cannot find anywhere in the templates that I can edit, to get it to work.

Any help much appreciated. sgs.png