<div id="wrap">

	<!-- section -->
	<div class="section">
		<div class="center">

			<button id="go">Фулскрин</button>

		</div>
	</div>
	<!--/section -->

</div>
html,
body {
	margin: 0;
	padding: 0;
	font-family: sans-serif;
	font-size: 16px;
	line-height: 1.4;
	color: #555;
	background: #fff;
}

* {
	box-sizing: border-box;
}

#wrap {
	position: relative;
}

.section {
	padding: 40px;
}

#line {
	font-size: 24px;
	margin-bottom: 20px;
}

#go {
	padding: 20px;
	cursor: pointer;
}
View Compiled
var goBtn = document.getElementById('go');

goBtn.onclick = function () {
	document.documentElement.requestFullscreen();
}

goBtn.onclick = function () {
	launchFullScreen(document.documentElement);
}

function launchFullScreen(element) {

	if (element.requestFullScreen) {
		element.requestFullScreen();
	} else if (element.mozRequestFullScreen) {
		element.mozRequestFullScreen();
	} else if (element.webkitRequestFullScreen) {
		element.webkitRequestFullScreen();
	}
}

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/3.4.1/jquery.min.js