IMPORTANT: clean-css is now in a maintenance mode. PRs are still welcome, and I will try do an occasional bugfix relase.

Precheck

• Do a quick search and make sure a bug has not yet been reported;
• do a quick check if the bug still exists in the latest patch version;
• finally, be nice and have fun!

Environment

• clean-css version - npm ls clean-css: 5.3.3
• node.js version - node -v: v20.6.1
• operating system: Windows 11 23H2 22631.2861

Configuration options

const CleanCSS = (await import("clean-css")).default;
new CleanCSS({});

Input CSS

@layer theme, layout, utilities;

Example from https://developer.mozilla.org/en-US/docs/Web/CSS/@layer

Actual output CSS

Nothing. And even ignore the following CSS rules.

Expected output CSS

@layer theme,layout,utilities;