[Deff]

Aetae,
Лан - Решать в конце концов ТС

<style type="text/css">
#s1.showFirst1 {display:none;}
#s2.showFirst1 {display:block;}
#ChangeBox2.showFirst1 {background: #F60; color: #FFF}
#ChangeBox1.showFirst1 {background: #FFF; color: #F60}

#s1.showFirst2 {display:block;}
#s2.showFirst2 {display:none;}
#ChangeBox2.showFirst2 {background: #FFF; color: #F60}
#ChangeBox1.showFirst2 {background: #F60; color: #FFF}
</style>


<script type="text/javascript">

var arrById='s2,s1,ChangeBox2,ChangeBox1';arrById = arrById.split(',');

function changClass(Class){
  for(var i in arrById) document.getElementById(arrById[i]).setAttribute('class',Class);
}

(function (){var a=0;
  toggleClass = function (){changClass('showFirst'+(1+a%2));a++;} 
  return toggleClass;
} () )

</script>