Introduction

Most mainstream web-browsers including Firefox now-a-days come with a feature where your browser sends your preferred colorshemes to websites when you visit them. If the website supports this feature, then you are presented with a light or dark version of the website based on your preference. In this post I will share how to manually configure it in Firefox.

prefers-color-scheme

prefers-color-scheme is a CSS feature that can be used by websites to detect if the browser has requested a light or a dark color theme. And if your browser sends the preference of dark theme and if a visited website chooses to implement an alternate dark CSS colorsheme then the web content will be displayed in dark mode. Here are the allowed values for prefers-color-scheme:

Debian Stretch, the current stable release of Debian now comes with Firefox ESR 60. One strange issue I have noticed with the out of the box configuration of Firefox on Debian is that it does not correctly render the Indic fonts on the websites. Most notable issue is that it breaks the connected letters while showing. Here's how I fixed it.

1. Install the fonts-indic package.
   

   sudo apt install fonts-indic



2. Now open Firefox and go to Preferences > General > Language and Appearance > Fonts & Colors and click on Advanced. Select the language you want to set fonts for from the "Fonts for" dropdown and select fonts with your specific language support for Serif and Sans-serif fonts, click Ok.

   Here's how my settings looks like: