diff --git a/chapter_rl_sys/index.md b/chapter_rl_sys/index.md
index f4eb349..f982d7b 100644
--- a/chapter_rl_sys/index.md
+++ b/chapter_rl_sys/index.md
@@ -14,6 +14,5 @@
 rl_sys_intro
 ros
 ros_code_ex
-
 summary
 ```