Merge branch 'person-tags-better' into 'master'

Highlighting of person mentions now better visible on low contrast screens and…

See merge request gitlab-org/gitlab-ce!20509

app/assets/stylesheets/bootstrap_migration.scss

@@ -110,7 +110,7 @@ code {
   padding: 2px 4px;
   color: $red-600;
   background-color: $red-100;
-  border-radius: 3px;
+  border-radius: $border-radius-default;
 
   .code > & {
     background-color: inherit;

app/assets/stylesheets/framework/gfm.scss

@@ -9,12 +9,8 @@
 
 .gfm-project_member {
   padding: 0 2px;
-  border-radius: #{$border-radius-default / 2};
-  background-color: $user-mention-bg;
-
-  &:hover {
-    background-color: $user-mention-bg-hover;
-  }
+  background-color: $blue-100;
+  border-radius: $border-radius-default;
 }
 
 .gfm-color_chip {