Pure CSS로 '도구 설명 꼬리' 효과를 어떻게 만들 수 있나요?

<div>Cool Trick:
    <div class="tooltiptail"></div>
</div>
<br>

<div>How do I get this effect with only CSS?
    <div class="anothertail"></div>
</div>

.tooltiptail {
    display: block;
    border-color: #ffffff #a0c7ff #ffffff #ffffff;
    border-style: solid;
    border-width: 20px;
    width: 0px;
    height: 0px;
}

.anothertail {
    background-image: url(http://static.jqueryfordesigners.com/demo/images/coda/bubble-tail2.png);
    display: block;
    height: 29px;
    width: 30px;

}

#tailShadow {
    position: absolute;
    bottom: -8px;
    left: 28px;
    width: 0;
    height: 0;
    border: solid 2px #fff;
    box-shadow: 0 0 10px 1px #555;
}

#tailShadow {
    position: absolute;
    bottom: -8px;
    left: 28px;
    width: 0;
    height: 0;
    border: solid 2px #fff;
    -moz-box-shadow: 0 0 10px 1px #555;
    -webkit-box-shadow: 0 0 10px 1px #555;
    box-shadow: 0 0 10px 1px #555;
}