[v4] Single class detection not working in Gleam without whitespace

[okkdev]

What version of Tailwind CSS are you using?

v4.0.0-beta.9

What build tool (or framework if it abstracts the build tool) are you using?

Vite v6.0.7

What version of Node.js are you using?

v23.2.0

What browser are you using?

Arc (Chromium)

What operating system are you using?

macOS

Reproduction URL

• Clone this repo: https://github.com/okkdev/tailwindcss4-class-detection-bug-repro/
• run npm dev
• notice that bg-red-200 is missing

Describe your issue

Tailwind doesn't detect the class inside this list [class("bg-red-200")] at https://github.com/okkdev/tailwindcss4-class-detection-bug-repro/blob/main/src/main.gleam#L33

It only works if there is a whitespace somewhere inside of the square braces.
As shown here: https://github.com/okkdev/tailwindcss4-class-detection-bug-repro/blob/main/src/main.gleam#L35
and here: https://github.com/okkdev/tailwindcss4-class-detection-bug-repro/blob/main/src/main.gleam#L38

It would be awesome if there was a way to customize the detection to support more languages like Gleam, instead of having to rely on the automatic detection.