JSFiddle - React, Tailwind, and code Playground

HTML

<!DOCTYPE HTML>
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
<title>Задание 3</title>
<link rel="stylesheet" type="text/css" href="task3.css" media="all">
</head>
<body>
 <div class="box">
  <div class="inner_box">
   <h2>Заголовок <i></i></h2>
   <div class="ininner_box">
   Содержание блока
   </div>
  </div>
 </div>
</body>
</html>

CSS

body{
 padding: 8px;
 background: url(http://htmlbook.ru/example/images/redline.png);
}

.box{
 background-color: rgba(102, 204, 204, 0.7); 
 border: 2px solid #004c3b;
 padding: 7px;
 -webkit-border-radius: 5px;
 -moz-border-radius: 5px;
 border-radius: 5px; 
 min-height: 100px;
}

.inner_box{
 background: #edecde;
 border: 1px solid #666;
 -webkit-border-radius: 6px;
 -moz-border-radius: 6px;
 border-radius: 6px; 
 min-height: 50px;
}

.ininner_box{
 padding: 10px; 
 min-height: 47px;
}

h2{
 margin: 0;
 -webkit-border-top-left-radius: 6px;
 -webkit-border-top-right-radius: 6px;
 -moz-border-radius-topleft: 6px;
 -moz-border-radius-topright: 6px;
 border-top-left-radius: 6px;
 border-top-right-radius: 6px; padding: 0 0 0 10px;
 line-height: 33px;
 height: 33px;
 font-size: 16px;
 font-family: Arial;
 font-weight: normal;
 background: -moz-linear-gradient(#ffd800, #ffba00);
 background: -webkit-gradient(linear, 0 0, 0 100%, from(#ffd800), to(#ffba00));
 filter: progid:DXImageTransform.Microsoft.gradient(startColorstr='#ffd800', endColorstr='#ffba00');
 position: relative;
}

h2 i{
 display: block;
 position: absolute;
 border-color: #ffba00 transparent transparent;
 border-style: solid;
 border-width: 10px;
 height:0;
 width:0;
 position:absolute;
 bottom: -20px; 
 left: 6px;
}