Add header.divider (#282)

* Add header.divider

* Add exception for LHC

* Create nervous-ghosts-vanish.md

Author: simurai

.changeset/nervous-ghosts-vanish.md

@@ -0,0 +1,5 @@
+---
+"@primer/primitives": minor
+---
+
+Add `header.divider`

data/colors/themes/light_high_contrast.ts

@@ -210,6 +210,9 @@ const exceptions = {
     hunk: {
       numBg: get('scale.blue.1')
     }
+  },
+  header: {
+    divider: get('scale.gray.3')
   }
 }
 

data/colors/vars/component_dark.ts

@@ -26,6 +26,7 @@ export default {
   header: {
     text: alpha(get('scale.white'), 0.7),
     bg: get('scale.gray.8'),
+    divider: get('scale.gray.3'),
     logo: get('scale.gray.0')
   },
   headerSearch: {
@@ -153,7 +154,7 @@ export default {
 
   actionListItem: {
     inlineDivider: alpha(get('border.default'), 0.48),
-  
+
     default: {
       hoverBg: alpha(get('scale.gray.2'), 0.12),
       activeBg: alpha(get('scale.gray.2'), 0.2),

data/colors/vars/component_light.ts

@@ -26,6 +26,7 @@ export default {
   header: {
     text: alpha(get('scale.white'), 0.7),
     bg: get('scale.gray.9'),
+    divider: get('scale.gray.6'),
     logo: get('scale.white')
   },
   headerSearch: {
@@ -154,7 +155,7 @@ export default {
 
   actionListItem: {
     inlineDivider: alpha(get('border.default'), 0.48),
-    
+
     default: {
       hoverBg: alpha(get('scale.gray.2'), 0.32),
       activeBg: alpha(get('scale.gray.2'), 0.48),