diff --git a/doc/langref.html.in b/doc/langref.html.in
index 9aa106fb54afb11ba68a5f5ff71c03aff25de7f4..3515875c87ce0afa4e811d633eb2864683465f65 100644
--- a/doc/langref.html.in
+++ b/doc/langref.html.in
@@ -85,7 +85,6 @@
       #main-wrapper {
         display: flex;
         flex-direction: column;
-        height: 100vh;
       }
 
       #contents-wrapper {
@@ -106,6 +105,11 @@
         #main-wrapper {
             flex-direction: row;
         }
+        #toc {
+            height: 100vh;
+            position: sticky;
+            top: 0;
+        }
         #contents-wrapper, #toc {
             overflow: auto;
         }