var refAct = 0;
var classStr = 'class';
if(navigator.appVersion.indexOf('MSIE 6.0') > -1) {
  classStr = 'className';
}
else {
  classStr = 'class';
}

function changeRef(id)
{
  var boxes = jQuery('#customers .inside');
  var numbers = jQuery('#customers .slider li');
  var i;
  
  for(i = 0;i < boxes.length;i++) {
    if(i == refAct) {
      boxes[i].setAttribute(classStr, 'inside hidden');
      numbers[i].setAttribute(classStr, '');
    }
    if(i == id) {
      boxes[i].setAttribute(classStr, 'inside');
      numbers[i].setAttribute(classStr, 'active');
    }
  }
  
  refAct = id;
}

function prevRef()
{
  changeRef(refAct == 0 ? 5 : refAct - 1);
}

function nextRef()
{
  changeRef(refAct == 5 ? 0 : refAct + 1);
}