Use an RTL build(ar/he).
Windows 7 x 64
Steps to reproduce
- Launch Firefox and go to https://longform.org/best .
- Click on the Reader view icon from the Menu bar.
- Click on the "Type Controls" button.
There should be 3 themes to choose from: Light, Sepia and Dark.
There are 4 themes.
Will look for one ASAP.
There is a screenshot showing the problem in more detail.
In this particular case i tested on macOS with Dark Theme enabled at OS level; as such, 2 different Dark Mode buttons are showing. On win7, the test was done using Light Theme at OS level; 2 different Light mode buttons are showing. See the attachment for more detail.