playground: Enable realtime streaming of playground output.

Added style for service error output.
diff --git a/client/stylesheets/playground.css b/client/stylesheets/playground.css
index edfa219..196a696 100644
--- a/client/stylesheets/playground.css
+++ b/client/stylesheets/playground.css
@@ -100,6 +100,10 @@
   color: #d01716;
 }
 
+.pg .console .text .svc-stderr {
+  color: #d01716;
+}
+
 .pg .console .text .debug {
   color: #455ede;
 }