title: @import not working in Laravel Mix
body: <p>I'm having a style.css file which is having the following code:</p>
  
  <pre><code>@import url("bootstrap.css");                       
  @import url("icons.css");
  @import url("plugins/revolutionslider.css");
  @import url('https://fonts.googleapis.com/css?family=Raleway:300,400,500,600,700');
  @import url('https://fonts.googleapis.com/css?family=Open+Sans:600,700');
  </code></pre>
  
  <p>and below some more css code. Now I'm trying to compile css file with Laravel Mix, so below is my  <code>webpack.mix.js</code> file's code:</p>
  
  <pre><code>    mix.styles([
      'resources/assets/custom/css/style.css',
      'resources/assets/custom/css/colors/main.css'
  ], 'public/css/app.css');
  </code></pre>
  
  <p>Now, after running <code>npm run dev</code>, instead of importing all those css files, it's below is the output which I get on compiled file <code>app.css</code></p>
  
  <pre><code>@import url("bootstrap");
  @import url("icons.css");
  @import url("plugins/revolutionslider.css");
  @import url('https://fonts.googleapis.com/css?family=Raleway:300,400,500,600,700');
  @import url('https://fonts.googleapis.com/css?family=Open+Sans:600,700');
  </code></pre>
  
  <p>So why is it not importing the code inside those files? What am I doing wrong?</p>
  
  <p>Thanks to everyone in advance.</p>