diff --git a/static/skin/viewer.js b/static/skin/viewer.js
index 0426aea0e..db7bc2ba8 100644
--- a/static/skin/viewer.js
+++ b/static/skin/viewer.js
@@ -198,7 +198,10 @@ function updateToolbarVisibilityState() {
 }
 
 function handle_visual_viewport_change() {
-  contentIframe.height = window.visualViewport.height - contentIframe.offsetTop - 4;
+  const wh = window.visualViewport
+           ? window.visualViewport.height
+           : window.innerHeight;
+  contentIframe.height = wh - contentIframe.offsetTop - 4;
 }
 
 function handle_location_hash_change() {
diff --git a/test/server.cpp b/test/server.cpp
index 0ec08c821..db34315fc 100644
--- a/test/server.cpp
+++ b/test/server.cpp
@@ -73,7 +73,7 @@ const ResourceCollection resources200Compressible{
   { DYNAMIC_CONTENT, "/ROOT/skin/taskbar.css" },
   { STATIC_CONTENT,  "/ROOT/skin/taskbar.css?cacheid=2cbac34b" },
   { DYNAMIC_CONTENT, "/ROOT/skin/viewer.js" },
-  { STATIC_CONTENT,  "/ROOT/skin/viewer.js?cacheid=430d45b0" },
+  { STATIC_CONTENT,  "/ROOT/skin/viewer.js?cacheid=03fd97ee" },
   { DYNAMIC_CONTENT, "/ROOT/skin/fonts/Poppins.ttf" },
   { STATIC_CONTENT,  "/ROOT/skin/fonts/Poppins.ttf?cacheid=af705837" },
   { DYNAMIC_CONTENT, "/ROOT/skin/fonts/Roboto.ttf" },
@@ -302,7 +302,7 @@ R"EXPECTEDRESULT(    <link type="text/css" href="./skin/taskbar.css?cacheid=2cba
     <link type="text/css" href="./skin/css/autoComplete.css?cacheid=08951e06" rel="Stylesheet" />
     <script type="module" src="./skin/i18n.js?cacheid=6da2bca0" defer></script>
     <script type="text/javascript" src="./skin/languages.js?cacheid=fe100348" defer></script>
-    <script type="text/javascript" src="./skin/viewer.js?cacheid=430d45b0" defer></script>
+    <script type="text/javascript" src="./skin/viewer.js?cacheid=03fd97ee" defer></script>
     <script type="text/javascript" src="./skin/autoComplete.min.js?cacheid=1191aaaf"></script>
       const blankPageUrl = root + "/skin/blank.html?cacheid=6b1fa032";
           <label for="kiwix_button_show_toggle"><img src="./skin/caret.png?cacheid=22b942b4" alt=""></label>