This is "relative color" syntax, it works with a range of color spaces/color functions. The key is the "from" at the front. Here's the MDN documentation: https:

This is "relative color" syntax, it works with a range of color spaces/color functions. The key is the "from" at the front. Here's the MDN documentation: https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_colors/Relative_colors https://developer.mozilla.org/en-US/docs/Web/CSS/CSS_colors/...