Post blocks with background and space between

You can see what I have active currently at https://www.andyfwood.com/wordpress

I’ve done all kinds of searching around on other peoples issues, but still can’t seem to make this work the way I want it. Basically everything is one uniform sold black background (all the posts). I’d like a clear space between each post its a block.

How I made the background color black was I used…

#content {
	line-height: normal;
background-color:#000;
	}

After that I tried playing around with the code below but it justs moves the text elements doesn’t actually separate the black background per post.

#content .post {
  margin: 2em 0em 0em;
}

On one other note I can not figure out why my font is sticking as bold. I’ve used the same font through out the site where it’s not bold. I went through the style.css and found nothing that was indicating it to be bold. No B, Strong, or Weight tags that would suggest it being bold.

Thanks in advance for all your help!