Edit in JSFiddle

Result
JavaScript
HTML

$(document).ready(function () {
                $("#findButton").click(function () {
                    $("#findDiv").find('em').css({ 'font-size': '40px', 'color': 'Aqua' });
                });
            });

<html>
        <head>
        <title>find</title>
        </head>
        <body>
        <div id="findDiv" style="height:100px;">
        <p>This is an example for <em>find</em> method.</p>
        </div>
        <input type="button" id="findButton" value="Click" />
        <input type="button" value="Reset" onclick="location.reload()" />
        </body>
        </html>