// JavaScript Document

$("#mydiv").children().each(function(i) {
	// do stuff to children
	$(this).css("top", 0);

});


var el = document.getElementById("mydiv");
var children = el.getElementsByTagName("div");
for (var i=0; children.length; i++) {
	var child = children[i];
	child.style.top = "0px";
}