CSS Parsing error for `:scroll-button`

Although still [experimental](https://developer.mozilla.org/en-US/docs/Web/CSS/::scroll-button), `:scroll-button` is not getting parsed.

Below is the error message via Next.js Turbopack, but the error message is from Lightning CSS.

<img width="1009" height="546" alt="Image" src="https://github.com/user-attachments/assets/11c1e737-c812-4376-babe-c68fdd372dc8" />