header style added to advent items

content/u/advent-calendar/03/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: /u/image/cards/advent-3.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 03:
 ---
 headline2: 20% off 

content/u/advent-calendar/04/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: u/image/cards/advent-4.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 04:
 ---
 headline2: 20% off 

content/u/advent-calendar/05/contents.lr

@@ -10,6 +10,12 @@ subtitle:
 ---
 image: /u/image/cards/advent-5.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 5:
 ---
 headline2: 20% off

content/u/advent-calendar/06/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: /u/image/cards/advent-6.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 6:
 ---
 headline2: 20% off 

content/u/advent-calendar/07/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: /u/image/cards/advent-7.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 7:
 ---
 headline2: 20% off

content/u/advent-calendar/10/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: /u/image/cards/advent-10.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 10:
 --- 
 headline2: 20% off 

content/u/advent-calendar/11/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: /u/image/cards/advent-11.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 11:
 ---
 headline2: 20% off

content/u/advent-calendar/12/contents.lr

@@ -10,6 +10,12 @@ subtitle: 20% off for 10 limited VMs
 ---
 image: /u/image/cards/advent-12.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 12:
 --- 
 headline2: 20% off

content/u/advent-calendar/13/contents.lr

@@ -10,6 +10,12 @@ subtitle:
 ---
 image: /u/image/cards/advent-13.jpg
 ---
+header_background_color: #C12107
+---
+header_text_color: text-light
+---
+nav_classes: navbar-dark
+---
 headline1: Surprise 13:
 ---
 headline2: 20% off