normalizeCharset

Ensures that only a single @charset is present in the CSS file, and moves it to the top of the document. This prevents multiple, invalid declarations occurring through naïve CSS concatenation. Note that by default, new @charset rules will not be added to the CSS.

Example

Input

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

Output

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