Function Hover Case

<div id="rectangle" onmouseover="her()" onmouseout="ovher()"></div>

#rectangle{
  width:100px;
  height:100px;
  background-color:red;
}

var hRectangle=document.getElementById('rectangle').style;
function her()
{
  hRectangle.width='200px';
  hRectangle.height = '200px';
  hRectangle.background='#ccc';
}
function ovher()
{
  hRectangle.width='100px';
  hRectangle.height = '100px';
  hRectangle.background='red';
}