diff --git a/_quarto.yml b/_quarto.yml
index 97d5eb8d..4b543ab4 100644
--- a/_quarto.yml
+++ b/_quarto.yml
@@ -25,6 +25,7 @@ book:
 
   sidebar:
     search: true
+    collapse-level: 1	
 
   page-navigation: true
   title: "MACHINE LEARNING SYSTEMS"