get size of product from tag li without checkbox when submit add to cart

[eluser]teddy[/eluser]
Thank you all guys, my problem is solved, this is my script,

$(document).ready(function(){
$('#kich_co_info li a').click(function(e)
{
var size=$(this).text();

e.preventDefault();
$(this).css({'color':'#F55D2D','font-weight':'bold'});
$("#kich_co_info li a").not(this).css({'color':'#222','font-weight':'normal'});
$.ajax({
url:'http://xyz.com/products/size/',
data:{"size"ize},
type:'post',
success:function(data){ /*alert("second success:"+size);*/ }

})
});

});


At frontend I show details of product with some size like : S, M, L or color of clothes and when users click on it the text or background will be change, that all I want

Above code I can only changed color text of li element (and save text size info to session) but I can't change the background of li element, if someone know how to change background was clicked before there is more choice for me, thank all for reply my topic