css-minifier: An [unsupported-css-nesting] warning is displayed for @page margin-at-rules when the target doesn't support CSS nesting

[PHoltom-Sequiter]

With a css file containing a margin-at-rule, like so:

@page {
	@top-left {
		content: "Anything";
	}
}

Attempting to minify with a target that doesn't support CSS nesting, for example .\node_modules\.bin\esbuild .\test.css --minify --target=chrome87

Results in a warning

▲ [WARNING] CSS nesting syntax is not supported in the configured target environment ("chrome87") [unsupported-css-nesting]

    test.css:2:1:
      2 │   @top-left {
        ╵   ~~~~~~~~~

Support for this particular nesting predates CSS nesting by quite a bit: MDN Docs

The output generated appears to be fine, in the above example the result is @page{@top-left{content:"Anything"}} but is there anything that can be done about the warning?

[evanw]

I'll look into it. In the meantime, you can disable the warning with --log-override:unsupported-css-nesting=silent.