var count = 0;
var $console = $('#console');
var $content = $('#content');
var i=0;
function addLine() {
  var line = '<span class="line ';
  var out = count.toString();
  if (count > 0) {
    if (count % 3 == 0) line += 'f';
    if (count % 5 == 0) line += 'b';
  }
  
  line += '" style="margin-left: ';
  line += 400 + 25 * Math.sin(i) * 6;
  line += 'px;">' + out + '</span><br />';
  $(line).appendTo('#content');
  i += 0.25;
  if ($content.height() > $console.height()) {
      var oldTop = $content.css('top');
    	var newTop = parseFloat(oldTop) - 20;
    console.log(oldTop, newTop);
    $('#content').css('top', newTop + 'px');
  }
  count ++;
}

setInterval(addLine, 200);