Edit in JSFiddle

<div id="myDiv">
    <p id="myP"> <em>This is the target element</em>

    </p>
</div>
<input type="button" id="button1" value="In Efficient" />
<input type="button" id="button2" value="Efficient" />
<input type="button" id="button3" value="Reload" onclick="location.reload();" />

$(document).ready(function () {
    $("#button1").click(function () {
        $("body #myDiv #myP em").css("color", "red");
    });
    $("#button2").click(function () {
        $("#myP").find("em").css("color", "red");
    });
});