works very well and does what it says, might take some learning to understand how it works but after that its amazing. 5 stars

It can not Grayscale mode.
Not found Grayscale button.
No color design.
サイトごとにグレースケール表示をかんたんに切り替えできると思いましたが、そうではありませんでした。
グレースケールボタンはどこにもない。
このアドオンの画面は色彩設計がされていません。目が痛い。

Great Extension! One thing i would wish is a more structured font-management.

it feels pretty chaotic insering all fonts in just one line.
Maybe also integrate custom categories for the fonts.

I never write reviews. But this extension is gold. I created account just to say thank you.

Update: My firefox was broken. The extension works fine.