The Invert Colors add-on for Firefox will – as the name suggests – invert any colors on websites basically turning very dark looking websites into lighter ones and vice verse. The first run after the installation of the add-on will come as a shock for many users as the option is turned on globally by default. This means that every website will display with inverted colors in Firefox.
That’s probably not something that the user wants to see. The problem here is that the developer of the extension added the means to disable the add-on for selected websites but not the other way round. This means that there is no option to turn the add-on off globally and only activate it for specific sites. It is only possible to turn it on globally and deactivate it for specific websites.
The developer should think about adding that possibility to his add-on to make it more useful for users who want to invert colors on just a few websites. An alternative for the add-on is the Darken script for Greasemonkey which can darken the background of specific websites.


The Firefox add-on is currently experimental meaning that user’s have to log into the Mozilla website before they can download and install it.
Update: The add-on has been deleted from the Mozilla Firefox website. an alternative is the No Colors add-on for Firefox.
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Interesting addon. What, exactly, is it’s use though?
Or use this stylish css:
http://userstyles.org/styles/2187
Thanks for finding this Martin! I often invert the colours of my display for accessibility and comfort reasons (I’m only 31, but the eyes hurt). However, having the _images_ of websites reversed is a pain. This addon is exactly what I’ve been looking for! Thanks!
@guest:
I am using the style you suggested as the addon would not install. The style is great! I have been browsing for an hour now and I will take my break, but the eyes do not hurt! Thank you!
We have started a new project http://www.searchon.me to help understand trends in web searching. It is a project that needs a critical mass of users who basically install a simple firefox add-on that aggregates search data. We would welcome your help.
This is pretty much what I am looking.
Why, why did they get rid of it. This plugin was perfect. Then I had to get a new firefox, and I lost it forever. That “replacement” sucks. This is a very, very, very sad day for me. I can’t find ANYTHING for firefox that inverts colors on a web page. Anywhere. I’ve googled for HOURS…
So sorry to hear it. Please let me know if you eventually find something…