div внутри другого diva

        <style>
         .dynamicDiv {   
             width: 30px;   
             height: 40px;     
             background-color: green;      
         }   
  </style>   
  <script type="text/javascript">   

         function createDiv() {  
             var divTag = document.createElement("div");   
             divTag.id = "div1";   
             //divTag.setAttribute("align", "center");  
              divTag.className = "dynamicDiv";  
     </script>   

<div id="timeline">    </div>
         
  <input id="btn1"    
                 type="button"    
                 value="create div"    
                 onclick="createDiv();" />