Improve header handling for post lists

CHDataManagement/Generator/HeaderElement.swift

@@ -95,7 +95,10 @@ extension HeaderElement: Hashable {
 extension HeaderElement: Comparable {
 
     static func < (lhs: HeaderElement, rhs: HeaderElement) -> Bool {
-        lhs.order < rhs.order
+        guard lhs.order == rhs.order else {
+            return lhs.order < rhs.order
+        }
+        return lhs.content < rhs.content
     }
 }