[Deff]

<script type="text/javascript" src="http://yandex.st/jquery/1.7.2/jquery.min.js"></script>
<script type="text/javascript">
$(document).ready(function(){
$(".reg_form div input").animate({opacity:'0.4'},0)
	$(".reg_form div input").click(function(){
		$(".reg_form div input").removeClass("active")
		$(this).addClass("active");		
		$(this).animate({opacity:'1'},"slow");
		$(".reg_form div input").not(".active").animate({opacity:'0.4'},"slow");	
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</script>
<form action="reg.php" method="post" class="reg_form">
	<div class="inp"><input type="text" name="name" value="Ваше имя" /></div>
    <div class="inp"><input type="text" name="fname" value="Ваша фамилия" /></div>
    <div class="inp"><input type="text" name="mail" value="Ваш маил" /></div>
    <div class="inp"><input type="password" name="pass" value="Ваш пароль" /></div>
</form>