JSFiddle - React, Tailwind, and code Playground

HTML

<html>
	<head>
			<title>Nauka bootstrapa</title>
			<link href="style.css" rel="stylesheet" type="text/css">
	
	</head>
	
	<body>
	
		
		<header>
			<div class = "class1">
				<h1>MOJA SUPER STRONA</h1>
			</div>
			
		
		</header>
			
	
	
	</body>

</html>

CSS

*
{
	margin:0;
	padding:0;
}

body
{
	font-family:tahoma;
}

.class1
{
	position:absolute;
	width:1140px;
	top: 50%;
	left: 50%;
	transform:translate(-50%,-50%);
}

header
{
	background-image: url('img1.jpg');
	heigth:100vh;
}