diff --git a/content/notes/21-data-link-layer.md b/content/notes/21-data-link-layer.md
index 0534ec8fe..1459d0c34 100644
--- a/content/notes/21-data-link-layer.md
+++ b/content/notes/21-data-link-layer.md
@@ -20,7 +20,6 @@ sr-ease: 250
 	- layer-2 packet: frame, encapsulates datagram
 		- ![](https://i.imgur.com/9RcK8WD.png)
 
-
 services
 - framing, link access:
 	- encapsulate datgram into frame, add head, trailer