diff --git a/www/index.html b/www/index.html
index 06a4b0cb..f66bdff0 100644
--- a/www/index.html
+++ b/www/index.html
@@ -100,13 +100,14 @@
                         </p>
                     </div>
                     <p style="padding-top:10px;">
-                        This application (apart from the PWA version) is packaged with only a sample ZIM archive of the top 100 Wikipedia articles
-                        so that you can get a feel for how offline Wikipedia browsing works. You will need to downloaded an offline ZIM archive and
-                        store it on your device. You can do this from the <b>Configuration page&nbsp;<span class="glyphicon glyphicon-wrench"></span></b>,
+                        This application may be packaged with a sample ZIM archive of the top 100 Wikipedia articles so that you can get a feel for how
+                        offline Wikipedia browsing works. For the full experience you <strong>must download an offline ZIM archive</strong> and store it
+                        on your device! You can do this from the <b>Configuration page&nbsp;<span class="glyphicon glyphicon-wrench"></span></b>,
                         or else see the <b>About page&nbsp;<span class="glyphicon glyphicon-info-sign"></span></b> for more information.
                     </p>
                     <p>
-                        For the full experience you <strong>must</strong> download a ZIM archive and store it on your device! Alternatively, if you only want Wikivoyage or WikiMed in English, look for "Wikivoyage by Kiwix" or "WikiMed" in the Store and install those apps instead.
+                        Alternatively, if you only want Wikivoyage or WikiMed in English, look for "Wikivoyage by Kiwix" or "WikiMed" in the Microsoft Store
+                        (Windows 10) and install those apps instead.
                     </p>
                     <p>
                         Kiwix JS is <b>free</b> and <b>open source</b>. If you like it, please leave a positive review. Constructive feedback and help with
@@ -619,7 +620,7 @@
                                         <label class="checkbox" title="Tap three times for dark | auto | light">
                                             <input type="checkbox" name="cssUIDarkTheme" id="cssUIDarkThemeCheck">
                                             <span class="checkmark"></span>
-                                            <b>Set dark mode for User Interface</b>: [ <b><span id="cssUIDarkThemeState"></span></b> ] (<i>auto</i> mode uses UWP system Settings if available)
+                                            <b>Set dark mode for User Interface</b>: [ <b><span id="cssUIDarkThemeState"></span></b> ] (<i>auto</i> mode uses OS Settings if available)
                                         </label>
                                         <label class="checkbox" title="Tap three times for dark | auto | light">
                                             <input type="checkbox" name="cssWikiDarkTheme" id="cssWikiDarkThemeCheck">
diff --git a/www/js/app.js b/www/js/app.js
index ea82ce82..c168ee61 100644
--- a/www/js/app.js
+++ b/www/js/app.js
@@ -1246,6 +1246,7 @@ define(['jquery', 'zimArchiveLoader', 'uiUtil', 'util', 'cache', 'images', 'sett
 
         function initializeUISettings() {
             var checkAuto = params.cssUITheme == 'auto' || params.cssTheme == 'auto';
+            // Support for UWP
             if (checkAuto && typeof Windows !== 'undefined' && Windows.UI && Windows.UI.ViewManagement) {
                 uiSettings = new Windows.UI.ViewManagement.UISettings();
                 uiSettings.oncolorvalueschanged = function () {
@@ -1253,6 +1254,14 @@ define(['jquery', 'zimArchiveLoader', 'uiUtil', 'util', 'cache', 'images', 'sett
                     if (params.cssTheme == 'auto') switchCSSTheme();
                 };
             }
+            // Support for other contexts (Firefox, Chromium, Electron, NWJS)
+            if (checkAuto && window.matchMedia('(prefers-color-scheme)').media !== 'not all') {
+                uiSettings = window.matchMedia('(prefers-color-scheme:dark)');
+                uiSettings.onchange = function () {
+                    if (params.cssUITheme == 'auto') cssUIThemeGetOrSet('auto');
+                    if (params.cssTheme == 'auto') switchCSSTheme();
+                };
+            }
         }
         // Code below is needed on startup to show or hide the inverted dark theme checkbox; 
         // similar code also runs in switchCSSTheme(), but that is not evoked on startup
@@ -1300,15 +1309,18 @@ define(['jquery', 'zimArchiveLoader', 'uiUtil', 'util', 'cache', 'images', 'sett
         });
 
         function cssUIThemeGetOrSet(value, getOnly) {
-            if (value == 'auto') {
+            if (value === 'auto') {
+                value = 'light'; // Default that most people expect
                 if (uiSettings) {
                     // We need to check the system theme
-                    // Value 0 below is the 'background' constant in array Windows.UI.ViewManagement.UIColorType
-                    var colour = uiSettings.getColorValue(0);
-                    value = (colour.b + colour.g + colour.r) <= 382 ? 'dark' : 'light';
-                } else {
-                    // There is no system default, so use light, as it is what most people will expect
-                    value = 'light';
+                    if (uiSettings.getColorValue) {
+                        // Value 0 below is the 'background' constant in array Windows.UI.ViewManagement.UIColorType
+                        var colour = uiSettings.getColorValue(0);
+                        value = (colour.b + colour.g + colour.r) <= 382 ? 'dark' : 'light';
+                    } else {
+                        // Generic support for modern browser contexts
+                        value = uiSettings.matches ? 'dark' : 'light';
+                    }
                 }
             }
             if (getOnly) return value;