How to set negative margin on last child post row?

[Grimlogic]

In my forums, I've set a margin for the .post attribute so that there's a break in between each post row, but this also creates an unwanted space on the last child post row.

.post {
	overflow: hidden;
	background: #12151a;
	margin: 0 0 5px 0;
}

The spaces circled in green are intentional, but how do I remove the one circled in red? Basically, I want the last child post row and the tfooter to be seamless.


I've tried editing some of the attributes in css3.css but I'm not able to see results.