JSFiddle - React, Tailwind, and code Playground

HTML

<h2>Заголовок</h2>
<p>
    Содержание блока 
</p>

CSS

body {font: 14px/14px Arial; padding: 20px;}
* { margin: 0; padding: 0;}
h2, p {
    background: #CEEBA6; 
    border: 1px solid #87C491;
}
h2 {
    display: inline-block;
    padding: 5px 10px;
    border-radius: 5px 5px 0 0;
    position: relative;
    border-bottom: none;
    margin-bottom: -1px;
}
h2:after {
    content: '';
    display: block;
    position: absolute;
    top: 0; right: 0; bottom: 0; left: 0;
    box-shadow: 0 0 7px #666;
    z-index: -1;
}
p {
    border-radius: 0 5px 5px 5px;
    padding: 10px;
    box-shadow: 0 0 7px #666;
    min-height: 100px;
}