I love what this extension does and how it does it. It's a good design, and the live updates as you tweak the settings really helps find the optimal setting for each site.
However, the "Disable" check box simply does not work. The only thing it disables is the Settings window. The extension continues to apply the current settings to every new tab you open. (It even applies them to the captions that accompany streaming videos from TED, YouTube, and Netflix!)
To actually disable it temporarily, you need to disable the extension itself. I have been doing that, but it's difficult.
It also lacks site-specific settings, which is a major drawback, especially for productivity sites (Gmail, Google Calendar, etc) that use custom shading and font colours extensively.
I expect the author intended it to be an elegant way to made global decisions for all sites, but made it too useful for users to want to use it like that.
We love the ability to customize the appearance of each website, and want to be able to have custom settings for each one. Unfortunately, this is a big change in the design, and I'm not sure the author is motivated to make this change.
So dear reviewers, PLEASE BE KIND when asking the author to take that big step, and to put in those hours! This is a free extension, and the work is completely voluntary, so we need to treat the author with respect!