<body>
<div class="myDiv1 myDiv2">This is div.</div>
<button id="myButton">Click Me</button>
<button onclick="location.reload()">Reset</button>
</body>
$(document).ready(function()
{
$("#myButton").click(function()
{
$(".myDiv1.myDiv2").css({'font-size':'20px','background-color':'Orange'});
});
});