Add padding to post_reply element

This adds a little space around the each reply on a post.

Signed-off-by: Alek Ratzloff <alekratz@gmail.com>

board/static/board/style.css

@@ -96,6 +96,10 @@ th {
     margin-left: 4px;
 }
 
+.post_reply {
+    padding: 2px;
+}
+
 .post_content:after {
     content: "";
     display: table;