As we wrote in our first article having dark and light Theme Modes has become important user experience element of every user interface framework.
Change the Theme Setting
Click on the [Window Button] and search Settings.
From the list of items – select Personalization.
From the list in the left Select Colors.
In the Colors Section There is a Combo/Select called [Choose your Color]. Change to Dark, Light or Custom.
Click on the Launchpad and Open System Preferences. From the menu Open the General Icon.
On the Top there is an Appearance Section. From there you could control the Theme Mode – Light, Dark and Auto.
You could read how to change the Themes on Ubuntu in this article:
https://itsfoss.com/dark-mode-ubuntu/
The Change Theme Menu in the Appearance Settings is present in the latest versions of the OS. You may be running an older version and you probably don’t want to upgrade and break other things. Then – execute the several commands and tools needed to make it work described in the above article.
Ultimately – there is an Extension of Chrome called Dark Reader, that does the job. It not only good tool for the Ubuntu Desktop, but it is also good for the other OSes. It reads the system flag and it applies the appropriate theme on other legacy web sites that currently don’t have integrated this feature.