firefox: split off zen browser

wiki/firefox.md

@@ -2,8 +2,10 @@
 
 [Firefox](https://www.mozilla.org/en-US/Firefox) is a free and open-source web
 browser.
-There are browsers that are based on Firefox and expand on its features like Zen browser.
-For this the usage is mostly the same.
+There are browsers that are based on Firefox and expand on its features like
+[Zen browser](/wiki/zen_browser.md).
+For this the usage is mostly the same except for the parts noted in the
+[Zen Browser entry](/wiki/zen_browser.md).
 
 ## Usage
 
@@ -109,7 +111,7 @@ The following add-ons provide translation options.
 The following add-ons add information to online shops.
 
 - [Fakespot](https://www.fakespot.com/) is an add-on made by Mozilla which displays additional
-  information on online shops, ebay and amazon. 
+  information on online shops, ebay and amazon.
   It can give shops, vendors and products a trust score which can be used as an alternative to
   reviews, which might be fake.
 

wiki/zen_browser.md

@@ -0,0 +1,19 @@
+# Zen Browser
+
+[Zen Browser](https://zen-browser.app) is a free and open-source web browser that was split off of
+[Firefox](/wiki/firefox.md) in 2024.
+The settings and usage of this browser is largely the same as Firefox'.
+This article only addresses things that differ from the normal usage - please refer to the
+[Firefox entry](/wiki/firefox.md) for everything else.
+
+## Usage
+
+The following section addresses different uses and add-ons of Zen Browser.
+
+### Enabling Dark/Light Mode 
+
+As explained in a
+[reddit post by Nureddinn](https://www.reddit.com/r/zen_browser/comments/1m4jn3y/zen_browser_stuck_at_light_mode/)
+the theme of Zen Browser can be changed by right-clicking the sidebar and selecting `Edit Theme`.
+In the pop-up configuration window the dark theme can be enabled by clicking the moon, the light
+theme by clicking the sun and the system default option by clicking the star.