fixed & added "postcss" config and "autoprefixer" settings

build/webpack.bundle.conf.js

@@ -4,6 +4,7 @@ const ExtractTextPlugin = require('extract-text-webpack-plugin')
 const OptimizeCSSPlugin = require('optimize-css-assets-webpack-plugin')
 const UglifyJsPlugin = require('uglifyjs-webpack-plugin')
 const { resolve } = require('path')
+const autoprefixer = require('autoprefixer')
 
 const config = {
   output: {
@@ -23,7 +24,15 @@ const config = {
         loader: 'vue-loader',
         options: {
           extractCSS: true,
-          cssSourceMap: true
+          cssSourceMap: true,
+          postcss: [
+            autoprefixer({browsers: [
+                '> 0.3%',
+                'last 7 versions',
+                'Android >= 4',
+                'Firefox >= 20'
+            ]})
+          ],
         }
       },
       {