Arbitrary px min-width utilities (min-[800px]) lose to smaller named breakpoints (sm) at the same width, unlike rem values

[LarsJK]

What version of Tailwind CSS are you using?

v4.1.13

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

postcss-loader 8.2.0

What version of Node.js are you using?

v22.19.0

What browser are you using?

Chrome

What operating system are you using?

macOS

Reproduction URL

https://play.tailwindcss.com/IryPEYKmlk?size=1254x807

Describe your issue

At a viewport width of exactly 800px:
• The left column is red-300 (coming from sm:bg-red-300), even though min-[800px]:bg-red-600 should apply.
• The right column is green-600 (coming from min-[50rem]:bg-green-600), which is the expected behavior.

This shows that arbitrary px values (min-[800px]) are always placed before named breakpoints like sm in the generated CSS, so the named breakpoint wins in the cascade. However, when using rem values (min-[50rem] = 800px), the arbitrary breakpoint appears after sm, so it correctly overrides.

Steps to reproduce:
1. Open the playground link above.
2. Resize the viewport to exactly 800px.
3. Observe that the left column is red-300 instead of red-600, while the right column is green-600.

Expected behavior:
At 800px, min-[800px]:bg-red-600 should override sm:bg-red-300, just like min-[50rem]:bg-green-600 does.

Actual behavior:
At 800px, sm:bg-red-300 wins over min-[800px]:bg-red-600, but only when the arbitrary breakpoint uses px.

[wongjn]

There is some documentation that is related to this:

Note that it's important to always use the same unit for defining your breakpoints or the generated utilities may be sorted in an unexpected order, causing breakpoint classes to override each other in unexpected ways.

Tailwind uses rem for the default breakpoints, so if you are adding additional breakpoints to the defaults, make sure you use rem as well.

This extends to arbitrary breakpoints too. Thus, you should use the 50rem version, or redefine your breakpoints as px values.

[LarsJK]

Thanks. I haven't seen that. I still think its very suprising behaviour and and would hope it could be sorted correct no matter what unit i use.