You are missing closing div tag when declaring layout. Please try the code below:
<!DOCTYPE html>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/default/easyui.css">
<link rel="stylesheet" type="text/css" href="http://www.jeasyui.com/easyui/themes/icon.css">
<script type="text/javascript" src="http://www.jeasyui.com/easyui/jquery-1.8.0.min.js"></script>
<script type="text/javascript" src="http://www.jeasyui.com/easyui/jquery.easyui.min.js"></script>
</head>
<body>
<div class="easyui-layout" fit="true">
<div region="west" split="true" title="A" style="width:250%;padding:5px;"> </div>
<div region="south" split="true" Title="B" style="height:250%;padding:5px"> </div>
<div region="center" title="C" style="padding:5px;"></div>
</div>
</body>
</html>
