Reduce the font size of post titles

Author: aaronshekey

lib/css/components/_stacks-post-summary.less

@@ -123,7 +123,7 @@
 
     .s-post-summary--content-title {
         display: inline-block;
-        font-size: @fs-subheading;
+        font-size: @fs-body3;
         margin-bottom: @su6;
         overflow-wrap: break-word;
         word-wrap: break-word;