Fixed double-space typo.
diff --git a/user_guide/userguide.css b/user_guide/userguide.css
index f93ff0d..b08f4fb 100644
--- a/user_guide/userguide.css
+++ b/user_guide/userguide.css
@@ -391,7 +391,7 @@
 
 .select {
  background-color: #fff;
- font-size:  11px;
+ font-size: 11px;
  font-weight: normal;
  color: #333;
  padding: 0;