diff --git a/packages/mermaid/src/styles.ts b/packages/mermaid/src/styles.ts
index 54c21ce03..d0eead51d 100644
--- a/packages/mermaid/src/styles.ts
+++ b/packages/mermaid/src/styles.ts
@@ -39,7 +39,7 @@ const getStyles = (
   }
 
   & .edge-thickness-normal {
-    stroke-width: 2px;
+    stroke-width: 1px;
   }
   & .edge-thickness-thick {
     stroke-width: 3.5px