(nevermind, found the corresponding issue on the github --
Yes, it is possible. Just open 'Global settings' tab and uncheck 'Run on all websites by default'.)
Would be nice if you could make it either blacklist or whitelist so I could leave it turned on but it only works on sites i whitelist instead of working on everything except sites i blacklist. *shrug*

Extensão muito boa tanto para o Firefox de Desktop e que pode ser instalada no Firefox Nightly para Android, funciona bem as funções de cores, mas precisa melhorar a resolução de tela da mesma quando executada no telefone.

This add-on is glorious, it is everything I ever wanted and helps keep my eyes in good shape!

super

This extension has allowed me to get the exact high contrast look I want for websites, seemingly not available from any existing themes - at least nothing I've been able to find. For that I give it full marks. Unfortunately I have to lower my rating because it slows down Firefox to such an extent that I had to disable it again.

Makes YouTube look like complete shit. Makes other websites look like they're from 2003. It's hard to make apps like this look good on all websites, so the majority end up looking awful.

Always get this message:

Midnight Lizard
Settings application failed. Refresh the page and try again.
QuotaExceededError: storage.sync API call exceeded its quota limitations.

Excellent extension since it works very well it changes the colors of the page, the brightness and the contrast to increase the readability and it brings the night mode is acceptable for its use.

App doesn't work in reality... works on sites like google... newegg and a.co but when you try and scroll down on any of these sites the page rips locks up then firefox warns you that the app is locked up. You can hit stop each time and it will load the page but thats not what this is for...

Basically i would avoid this because its broken there are other addons that actually work...