diff --git a/adev/shared-docs/components/navigation-list/navigation-list.component.scss b/adev/shared-docs/components/navigation-list/navigation-list.component.scss
index 16c11ab97d3..c2eb98aaf97 100644
--- a/adev/shared-docs/components/navigation-list/navigation-list.component.scss
+++ b/adev/shared-docs/components/navigation-list/navigation-list.component.scss
@@ -6,7 +6,7 @@
   list-style: none;
   overflow-y: auto;
   overflow-x: hidden;
-  height: 100vh;
+  height: 100dvh;
   padding: 0;
   margin: 0;
   padding-block: 1.5rem;
diff --git a/adev/src/app/app.component.scss b/adev/src/app/app.component.scss
index 36b3a2282c9..b4760cd53cc 100644
--- a/adev/src/app/app.component.scss
+++ b/adev/src/app/app.component.scss
@@ -40,6 +40,13 @@
     }
   }
 
+  // Lock the page behind the mobile primary-nav drawer. `clip` preserves the primary nav's sticky context.
+  @include mq.for-phone-only {
+    &:has(.adev-nav-primary--open) {
+      overflow: clip;
+    }
+  }
+
   &:has(.adev-home) {
     .adev-nav {
       width: 0;
diff --git a/adev/src/app/core/layout/secondary-navigation/secondary-navigation.component.scss b/adev/src/app/core/layout/secondary-navigation/secondary-navigation.component.scss
index fd655ebcd78..a793427d9db 100644
--- a/adev/src/app/core/layout/secondary-navigation/secondary-navigation.component.scss
+++ b/adev/src/app/core/layout/secondary-navigation/secondary-navigation.component.scss
@@ -35,6 +35,7 @@
 
   @include mq.for-tablet-landscape-down {
     position: absolute;
+    height: 100dvh;
   }
 
   @media (prefers-reduced-motion: no-preference) {