diff --git a/src/index.css b/src/index.css
index 271c67b..db81ed3 100644
--- a/src/index.css
+++ b/src/index.css
@@ -21,6 +21,7 @@
   --bg-active: #202020;
   --border-strong: #555;
   --danger-hover: #4f4f4f;
+  --tree-line: #5f5f5f;
 }
 
 body[data-theme="light"] {
@@ -41,6 +42,7 @@ body[data-theme="light"] {
   --bg-active: #e6e6e6;
   --border-strong: #b5b5b5;
   --danger-hover: #d6d6d6;
+  --tree-line: #9a9a9a;
 }