fix an error in css class change a duplicate h4 by a h5

Author: JoMessina

themes/middleware/assets/css/style.css

@@ -641,7 +641,10 @@ h1.single-title {
 
 .content h1,
 .content h2,
-.content h3 {
+.content h3,
+.content h4,
+.content h5,
+.content h6 {
   padding: 10px 0;
   position: sticky;
   top: 95px;