What version of Tailwind CSS are you using?

4.1.14

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

Vite 7.1.7

What version of Node.js are you using?

v20.19.5

What operating system are you using?

macOS

Reproduction URL

https://github.com/nlemoine/tailwind-resolve-bug

Describe your issue

When I'm using custom CSS vars to feed the config, value resolution fails for some values but for not for others.

✅ https://github.com/nlemoine/tailwind-resolve-bug/blob/1807ec46aa843f94f578802dadb2c0ce9517a54f/src/style.css#L6
❌ https://github.com/nlemoine/tailwind-resolve-bug/blob/1807ec46aa843f94f578802dadb2c0ce9517a54f/src/style.css#L7-L8

This creates inconsistent behavior regarding nesting and/or config naming.