Fix display of dropdown on case studies

assets/scss/_custom.scss

@@ -108,6 +108,10 @@ section {
 
       &.dropdown:hover {
         color: $medium-grey;
+
+        .dropdown-menu {
+          display: block;
+        }
       }
     }
   }
@@ -390,4 +394,4 @@ main.content {
       }
     }
   }
-}
+}