Widen the gap between listing items

.post/.hentry margin-bottom goes from the theme's 20px to 50px, giving
about 72px between items once the heading margins and the clearing
<br /> are counted.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/styles/global.css

@@ -1144,7 +1144,8 @@ h3.arc-src {
 .post, 
 .hentry, 
 .no-results {
-	margin-bottom: 20px;
+	/* Theme default was 20px; widened to give listing items clearer separation. */
+	margin-bottom: 50px;
 	
 }