title: How to extend css class with another style?
body: <p>I have nearly 30 classes and I want to apply this classes to my button element. I don't want to add class attribute for every button element. Is there any way to create a new button class like;</p>
  
  <pre><code>.button{
          .rounded-corner
          .corner
          .button-effective
          //another 20 classes
  }
  </code></pre>