diff --git a/frontend/src/index.css b/frontend/src/index.css
index ae8f922..e64338f 100644
--- a/frontend/src/index.css
+++ b/frontend/src/index.css
@@ -58,12 +58,20 @@ summary {
   cursor: pointer;
 }
 
-/* Global dark background */
+/* Global dark background - lock to viewport, no page-level scroll */
+html,
 body {
+  height: 100%;
+  overflow: hidden;
   background-color: var(--bg-primary);
   color: var(--text-primary);
 }
 
+#root {
+  height: 100%;
+  overflow: hidden;
+}
+
 /* Scrollbar styling */
 ::-webkit-scrollbar {
   width: 8px;