Add subtle box-shadow to thumbnail images

Author: jplatte

src/styles/app.scss

@@ -264,6 +264,7 @@ h3, .post h2, header h2 {
     margin-left: 15px;
     margin-bottom: 15px;
     clear: right;
+    box-shadow: 0 0 6px rgba(0, 0, 0, 0.3);
   }
 }