I spend a lot of time in front of the computer screen and this can be a real strain on the eyes. The easiest way for me to cope with this is to use dark themes and reduce the brightness of the screen. But these have their limitations. Using dark themes only affects window decorations and system wigdets, while decreasing brightness can make things near unreadable especially during the day time. Then there is the fact that most a lot of my time on the computer is spent in the web browser where themes have no effect and most pages are bright.
Enter Invert Colors. This is a great little experimental addon for Firefox. Basically it does does what it says on the box. It inverts the colors of web pages and removes background images. It works relatively well. So far only one site (www.hattrick.org) crashes Firefox with this Addon enabled. Gmail is not affected by this addon but this can be rectified easily with Gmail themes.
In general, sites continue to work well although some buttons and links do not appear on some sites e.g. the thumbs up and down icons for youtube comments. Pages look more "90s" without all the images and backgrounds. But the important thing is that it does what I expect it to do and that is dim down the pages and reduce eye strain. If you would rather Invert Colors does not modify a site, you can configure it to do just that. Simply disable it for the site and reload to see the page as it was meant to be.
I would recommend Invert Colors to someone who likes dark themes because they are easy one the eyes and can handle the less flashy and occasionally buggy web experience. I certainly think it is worth it. If you use some other method to achieve this effect, please do let me know!
Here are some example screenshots
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