Style soft folder separators

If you can see a folder but not its parents we concatenate the
breadcrumb into one link.

This styles folder separators inside these links a bit differently to
make them do a bit less visual separation than the ones outside the
links.

app/assets/stylesheets/components/message.scss

@@ -36,6 +36,13 @@
 
       &:hover {
         color: $link-hover-colour;
+
+        .message-name-separator {
+          &:before {
+            border-color: $link-hover-colour;
+          }
+        }
+
       }
 
       &:focus {
@@ -51,6 +58,16 @@
         }
 
       }
+
+      .message-name-separator {
+
+        margin-right: -2px;
+        margin-left: -2px;
+
+        &:before {
+          border-color: $link-colour;
+        }
+      }
     }
 
     &-separator {