Divider line between posts

I want a solid colored divider line between each post, which I have managed to get with this code in CSS – .post { margin: 0 0 1em 0; border-bottom: 2px solid #307D7E; }
But the problems are these: I want a line that doesn’t extend across the whole bottom of the post, but is smaller and centered. Secondly, I don’t want any line at the bottom of the last post; I am currently displaying seven posts in total. Thirdly, there is a nice spacing between the tag line and the divider line in sticky posts (for example, the post entitled “Some Directions for Writers”). But at the bottom of the regular posts, the solid line is tight to the tag line. I would like that spacing to be the same as in the stickly posts.
My URL is https://bibletruthchatroom.com/ And those are the head-exploding difficulties that I have wrestled and wrestled with, and cannot solve. Anyone know the solutions?