<div id="wrap">

	<!-- section -->
	<div class="section">
		<div class="center">

			<div id="chat">
				<div class="msg"></div>
			</div>
			
			<button id="send"><span>Send</span></button>

		</div>
	</div>
	<!--/section -->

</div>

html,
body {
	margin: 0;
	padding: 0;
	font-family: sans-serif;
	font-size: 16px;
	line-height: 1.4;
	color: #555;
	background: #fff;
}

* {
	box-sizing: border-box;
}

#wrap {
	position: relative;
}

.section {
	padding: 40px;
}

#chat {
	width: 400px;
	height: 400px;
	background: #eee;
	padding: 20px;
	margin: 0 auto 20px;
	overflow-y: auto;
}

.msg {
	padding: 10px;
	box-shadow: 0 2px 2px fade(#000, 5%);
	margin-top: 20px;
	position: relative;
	
	&::before {
		content: 'Message text';
		display: block;
	}
	
	&::after {
		content: '';
		display: block;
		position: absolute;
		top: 100%;
		width: 0;
		height: 0;
		border: 5px solid transparent;
	}
	
	&:first-child {
		margin-top: 0;
	}
	
	&:nth-child(2n-1) {
		margin-right: 60px;
		border-radius: 4px 4px 4px 0;
		background: #f9ff8b;
		
		&::after {
			left: 0;
			border-top-color: #f9ff8b;
			border-left-color: #f9ff8b;
		}
	}
	
	&:nth-child(2n) {
		margin-left: 60px;
		border-radius: 4px 4px 0 4px;
		background: #e7ffef;
		
		&::after {
			right: 0;
			border-top-color: #e7ffef;
			border-right-color: #e7ffef;
		}
	}
}

#send {
	display: block;
	padding: 10px;
	width: 400px;
	margin: auto;
	cursor: pointer;
}

$(function() {
	var $chat = $('#chat'),
		$msg = $chat.find('.msg').last(),
		$send = $('#send');
	
	$send.click(function() {
		$msg.clone().appendTo($chat);
		$chat.stop().animate({
			scrollTop: $chat.prop('scrollHeight') - $chat.height()
		}, 600);
	});
});