消息框尖尖

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="renderer" content="webkit">
    <title>Title</title>
    <style>
        .box{
             200px;
            height: 100px;
            border: 2px solid blue;
            margin: 100px auto;
            position: relative;
            border-radius: 20px;
        }
        .box:before{
            content: "";
            position: absolute;
             0;
            height: 0;
            top: 36px;
            left: -11px;
            border-right: 10px solid blue;
            border-top: 10px solid transparent;
            border-bottom: 10px solid transparent;
        }
        .box:after{
            content: "";
            position: absolute;
             0;
            height: 0;
            top: 36px;
            left: -8px;
            border-right: 10px solid white;
            border-top: 10px solid transparent;
            border-bottom: 10px solid transparent;
        }
    </style>
</head>
<body>
    <div class="box"></div>
</body>
</html>
Title