custom.css: @media blocks using range syntax are being dropped

[rameshvarun]

I have a custom.css with some media queries. I noticed at some point they stopped working on the live site, then after a CLI upgrade they stopped working locally as well. These queries previously worked in CLI version 4.2.1032.

Repro: add this to custom.css:

@media (width < 100rem) {
  .foo { display: none; }
}

Run mint dev then look at the page's <style data-custom-css-path="custom.css"> tag.

Expected: the @media block is in the output.