postcss-normalize-charset

Add necessary or remove extra charset with PostCSS

a{
  content: "©";
}

@charset "utf-8";
a{
  content: "©";
}

API

Type: boolean
Default: true

Pass false to stop the module from adding a @charset declaration if it was
missing from the file (and the file contained non-ascii characters).

See the PostCSS documentation for
examples for your environment.