Fixes #12914: Darken immediate children hr elements in jumbotrons

dist/css/bootstrap-rtl.css

@@ -5499,6 +5499,10 @@ a.list-group-item.active > .badge,
   font-weight: 200;
 }
 
+.jumbotron > hr {
+  border-top-color: #d5d5d5;
+}
+
 .container .jumbotron {
   border-radius: 6px;
 }

dist/css/bootstrap.css

@@ -4411,6 +4411,9 @@ a.list-group-item.active > .badge,
   font-size: 21px;
   font-weight: 200;
 }
+.jumbotron > hr {
+  border-top-color: #d5d5d5;
+}
 .container .jumbotron {
   border-radius: 6px;
 }

less/jumbotron.less

@@ -19,6 +19,10 @@
     font-weight: 200;
   }
 
+  > hr {
+    border-top-color: darken(@jumbotron-bg, 10%);
+  }
+
   .container & {
     border-radius: @border-radius-large; // Only round corners at higher resolutions if contained in a container
   }