title: Copying CSS classes
body: <p>Lets say that youre using Twitter Boostrap and you have their generic boostrap.css and other boostrap associated css files, and you want your own classes to have identical attributes to some of the given boostrap classes. To my understanding, you would not want to directly modify the css bootstrap files, but you would want to extend them by creating a custom.css file.</p>
  
  <p>So without touching the boostrap files. How would I replicate a boostrap class for my own class? Would the only way be to copy and paste from the boostrap.css file. Or is there a way to do</p>
  
  <pre><code>.myownclass {
      -- some command to replicate class 'alert alert-error' without repeating the CSS that has already been written
  }
  </code></pre>