I like this add-on. It works very well. However, it sometimes warns me that Firefox is slow, especially in Gmail, and I recommend not using this add-on in Gmail. Fortunately, this add-on allows you to create a blacklist of sites, so you don't have to turn off the add-on feature every time you open Gmail.

Postscript (2023/06/23):
In this add-on, some image characters (?) are displayed as characters instead of images. For example, when you open https://translate.google.co.jp, you might see characters like "swap_horiz" and "star_border". The reference image can be found at the following URL: https://imgur.com/gallery/vsjC8eL.

Love the idea but it's janky. Some sites look odd, which is fine as you can disable per site, but i currently can't as the shortcut isn't working and the menu has stopped working properly. Also causes a slight delay in loading sites that it's turned on for.

It crashed and make the sites loads more than normal, it takes too much resources that it needs too

Edit: Some sites have elements hidden while in Dark Mode. This has given me problems. I can edit the theme for such sites BUT - a suggestion: when editing/creating a theme, please make the default to only do so for the CURRENT SITE. "All sites" should be explicitly chosen by the user. Thank you!

This is a great add-on and I keep it ON by default. One important improvement for me would be this:
The default behavior for text fields (e.g., username/password fields) gives me yellow background with white lettering. It would be better to have either darker lettering or darker background. As it is, it is very hard (next to impossibile) to make out anything.
Other than that, perfect! THANK YOU :-)

Делает сайты темными достаточно корректно. Но при открытии любой страницы (даже уже темной), на экране появляется сначала белая страница, потом уже темная - это очень раздражает, особенно ночью. Ну и естественно расширение замедляет загрузку страниц.

Works great and deserves it's 5 stars.

works as one might expect, the auto detect dark mode feature is bit slow but that's a minor problem

I have been using this for years on Firefox and on Chrome and it works very well. It makes things not hurt eyes.