fix: respect map.annotation string

Author: keithamus

index.js

@@ -222,7 +222,7 @@ function css(css, file) {
             tasks.push(fs.outputFile(options.to, result.css))
 
             if (result.map) {
-              const mapfile = getMapfile(options.to)
+              const mapfile = getMapfile(opts)
               tasks.push(fs.outputFile(mapfile, result.map))
             }
           } else process.stdout.write(result.css, 'utf8')

lib/getMapfile.js

@@ -1,4 +1,8 @@
 'use strict'
-module.exports = function getMapfile(p) {
-  return `${p}.map`
+const path = require('path')
+module.exports = function getMapfile(options) {
+  if (options.map && typeof options.map.annotation === 'string') {
+    return path.join(path.dirname(options.to), options.map.annotation)
+  }
+  return `${options.to}.map`
 }