Describe the bug

When the CSS contains color relative syntax with calculation like this:

oklch(from var(--accent-l) calc(l + 0.05) c h);

We get an error at build time:

  Erroneous area:
1: l + 0.05
^..^ [postcss-calc]
57:3    ⚠  Lexical error on line 1: Unrecognized text.

Expected behaviour

We expect cssnano to detect relative color syntax as an exception.

Steps to reproduce

Add a relative color with a calculation in the css

oklch(from var(--accent-l) calc(l + 0.05) c h);

Run css nano with default parameters

Version

7.1.2

Preset

default

Environment

System:
    OS: Linux 6.14 Ubuntu 24.04.3 LTS 24.04.3 LTS (Noble Numbat)
    CPU: (32) x64 Intel(R) Xeon(R) Silver 4208 CPU @ 2.10GHz
    Memory: 52.71 GB / 62.52 GB
    Container: Yes
    Shell: 5.2.21 - /bin/bash

Package details

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Additional context

I tried added /* postcss-calc: ignore */ before problematic lines, but comment seems to be removed before processing the line.

I tried @csstools/postcss-relative-color-syntax but doesn't work either.

It seems that newer versions of postcss-calc support relative color syntax