jQuery(document).ready(function(){
    lastBlock = jQuery("#a1");
    maxWidth = 919;
    minWidth = 38;	

    jQuery("div#slider ul li a").click(
      function(){
    	jQuery(lastBlock).animate({width: minWidth+"px"}, { queue:false, duration:400 });
    	jQuery(this).animate({width: maxWidth+"px"}, { queue:false, duration:400});
		lastBlock = this;
      }
    );
});