Today I discovered that CSS relative colors exist.
https://blog.jim-nielsen.com/2021/css-relative-colors
https://ishadeed.com/article/css-relative-colors
https://developer.chrome.com/blog/css-relative-color-syntax
I have been AGONIZING over button hover effects and it was very frustrating to have to choose between verbose CSS variables, the filter property, or Sass.
Allowing quick color manipulation in CSS natively is my new favorite thing. This makes harmonious color schemes infinitely easier.
I tested it out on a :hover pseudo selector and it works!