Bug 1386160 - Add separators for each level 1 header to match the Photon visual spec. r=jaws

MozReview-Commit-ID: 7iyZuFgqrSQ

--HG--
extra : rebase_source : 2b35a451bb47298487d25c7d87e17dcdb576ca10

browser/themes/shared/incontentprefs/preferences.inc.css

@@ -95,11 +95,11 @@ caption > label {
 /**
  * The first subcategory title for each category should not have margin-top.
  */
-#generalCategory,
-#searchCategory,
-#browserPrivacyCategory,
-#firefoxAccountCategory {
-  margin-top: 0;
+
+.subcategory:not([hidden]) ~ .subcategory {
+  margin-top: 32px;
+  padding-top: 15px;
+  border-top: 1px solid rgba(12, 12, 13, 0.15);
 }
 
 .header-name {
@@ -107,10 +107,6 @@ caption > label {
   font-weight: 300;
 }
 
-.subcategory {
-  margin-top: 48px;
-}
-
 /* Category List */
 
 #categories {