title: how to output independent css use webpack?
body: <p>I have two entry file:pc.js and wap.js ,they require a same js (a.js);</p>
  
  <p>now a.js require two css file(a.css,b.css);</p>
  
  <p>In webpack 2 ,how to output two css file (a.css=>pc.css,b.css=>wap.css)? </p>