JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE HTML>
<html>
<head>
    <title>sol2</title>
    <style type="text/css">
    *
    {
        margin: 0;
        padding: 0;
        border: 0;
    }
    body
    {
        width: 100%;
        height: 100%;
    }
    div
    {
        background: #c9e39c;
        position: relative;
        border: 1px solid #a3d869;
        min-width: 200px;
        min-height: 100px;
        padding: 10px 20px;
        margin: 50px 100px;
        border-radius: 0 0 10px 10px;
        box-shadow: 0 0 5px rgba(0,0,0,.4);
        -webkit-box-shadow: 0 0 5px rgba(0,0,0,.4);
    }
    div h3
    {
        display: block;
        border: solid #a3d869;
        border-width: 1px 1px 0 1px;
        position: relative;
        font-size: 14pt;
        background: #c9e39c;
        padding: 5px 20px;
        height: 20px;
        max-width: 250px;
        float: left;
        margin: -42px 0 0 -21px;
        border-radius: 10px 10px 0 0;
        box-shadow: 0 -1px 5px rgba(0,0,0,.4);
        -webkit-box-shadow: 0 -1px 5px rgba(0,0,0,.4);
        white-space: nowrap;
    }
    div h3::before
    {
        content: "";
        width: 100%;
        height: 6px;
        bottom: -6px;
        left: 0;
        background:  #c9e39c;
        position: absolute;
    }
    div h3 span
    {
        display: block;
        max-width: 260px;
        overflow: hidden;
    }
    </style>
</head>

<body>
    <div>
        <h3>
            <span>
            Заголовок
            </span>
        </h3>
        <span>
        Содержание блока
        </span>
    </div>
</body>
</html>