title: Problems with scrolling inside a div by links
body: <p>I want to scroll inside a div (for example 150px down or up), but only "down" still works. I also dont know, if "animate" is the right way, it seems to be a bit laggy?</p>
  
  <p>The second plan ist, that the down or up link get opacity 50% when the content inside the div is top, or bottom.</p>
  
  <p>Can anyone help me?</p>
  
  <pre><code>     $('.down').click(function () {
      $( ".box" ).animate({
          scrollTop: '+=150px'
      });
  });
  $('.up').click(function () {
      $( ".box" ).animate({
          scrollBottom: '-=150px'
      });
  });
  </code></pre>
  
  <p>Here is my <a href="http://jsfiddle.net/8y1vc699/" rel="nofollow">fiddle</a></p>