Resizing height & width in percentage not pixel

I am using jQuery plugin for resizing the elements. Elements height & width is set in percentage (%) not in pixel. Whenever i re-size any element it's height & width changes to pixels which is fixed but i wanted this change in percentage.

I am sure there must be some technical issue for this but there would be solution too.

#parentDiv { height:100%; width:100%;}

.image { height: 25%; width: 25%; }  

<body>
<div id = "parentDiv">
    <div class="image" id="image1" onmouseover="resizeMe(this);"> </div>
    <div class="image" id="image2" onmouseover="resizeMe(this);"> </div>
</div>  

<script> 
  function resizeMe(obj) {
        $(#obj.id).resizable();  }

</body>

But once i re-size id=image1, below is HTML code. it contains the height & width size in pixels. Does anybody light on it, How can i manage to re-size in percentage only.

<div class="image" style="width: 345px; height: 52px;">