Try below..
$("#divContent").append(new_div).css( { "position":"relative" , "float":"left" , "top":"10px" , "padding":"5px" });
...
Also you can generate unique
id's for newly added
div's dynamically and write css for those div's containing positioning...
Ex
<style type="text/css">
#div1
{
position:relative;
float:left;
height:100px;
width:100px;
padding:5px;
border:solid 1px silver;
}
#div2
{
position:relative;
float:left;
height:50px;
width:50px;
padding:5px;
border:solid 1px silver;
}
</style>