JSFiddle - React, Tailwind, and code Playground

HTML

<!doctype html>
<title>Задание 2</title>
<h2>Заголовок</h2>
<div>
    Содержимое блокаfhngfjh
</div>

CSS

h2, div {
    background: #c9e39c;
    border: 1px solid #a3d869;
}
h2 {
    float: left;
    max-width: 250px;
    border-radius: 5px 5px 0 0;
    font: bold 15px Verdana, Arial, Helvetica, sans-serif;
    position: relative;
    border-bottom: 0;
    margin-bottom: -1px;
    padding: 5px 9px 6px;
}
h2::after {
    display: block;
    position: absolute;
    top: -1px;
    bottom: 0;
    left: -1px;
    right: -1px;
    -webkit-box-shadow: 0 0 5px #666;
    -moz-box-shadow: 0 0 5px #666;
    box-shadow: 0 0 5px #666;
    border-radius: 5px 5px 0 0;
    content: "";
    z-index: -1;
}
div {
    clear: left;
    border-radius: 0 5px 5px 5px;
    font: 14px Arial, Helvetica, sans-serif;
    -webkit-box-shadow: 0 0 5px #666;
    -moz-box-shadow: 0 0 5px #666;
    box-shadow: 0 0 5px #666;
    padding: 10px 9px;
    min-height: 100px;
}