loop/webui: add prettier
diff --git a/loop/webui/src/diff2.css b/loop/webui/src/diff2.css
index 5a7ad71..f716a01 100644
--- a/loop/webui/src/diff2.css
+++ b/loop/webui/src/diff2.css
@@ -61,7 +61,7 @@
   font-size: 16px;
   font-weight: bold;
   cursor: pointer;
-  box-shadow: 0 1px 3px rgba(0,0,0,0.2);
+  box-shadow: 0 1px 3px rgba(0, 0, 0, 0.2);
   opacity: 0.9;
   z-index: 100;
   user-select: none;