fix: paths in postcss sourcemap sources array (#500)

Author: bfanger

src/transformers/globalStyle.ts

@@ -75,6 +75,7 @@ const transformer: Transformer<Options.GlobalStyle> = async ({
 
   const { css, map: newMap } = await postcss(plugins).process(content, {
     from: filename,
+    to: filename,
     map: options?.sourceMap ? { prev: map } : false,
   });
 

src/transformers/postcss.ts

@@ -15,6 +15,7 @@ async function process({
 }) {
   const { css, map, messages } = await postcss(plugins).process(content, {
     from: filename,
+    to: filename,
     map: { prev: sourceMap, inline: false },
     parser,
     syntax,