What version of Tailwind CSS are you using?
4.1.15
What build tool (or framework if it abstracts the build tool) are you using?
Vite 7.1.11
What version of Node.js are you using?
Bun 1.3.0
What browser are you using?
N/A
What operating system are you using?
Windows
Reproduction URL
https://play.tailwindcss.com/nuCpVvYcjM
The reproduction is irrelevant, it happens only in dev.
Describe your issue
tailwindcss/vite 4.1.15 introduced a regression in dev regarding color opacity support.
