https://gist.github.com/raw/c6ca9ed14d388e6e7e8278cebc3dfb29/YouTube_Enhancer.user.js

YouTube_Enhancer.user.js

// ==UserScript==
// @name		YouTube Enhancer
// @namespace	http://iulianonofrei.com
// @version		0.5
// @author		Iulian Onofrei
// @updateURL	https://gist.github.com/raw/c6ca9ed14d388e6e7e8278cebc3dfb29/YouTube_Enhancer.user.js
// @match		https://youtube.com/*
// @match		https://www.youtube.com/*
// @require		https://gist.githubusercontent.com/raw/dab432d4b4bbb672896b/min.js
// @grant		GM_addStyle
// ==/UserScript==

(function() {
	'use strict';

	function setWide(isWide) {
		if (isWide) {
			document.body.classList.add("io-wide");
		} else {
			document.body.classList.remove("io-wide");
		}
	}

	var isWide = min.dom.getByClassName("watch-wide");

	setWide(isWide);

	min.dom.addObserver(function (mutations) {
		var
			node = mutations[0].target,
			isWide = node.className.indexOf("watch-wide") !== -1;

		setWide(isWide);
	}, min.dom.getById("page"), {attributes: true});

	min.gm.style({
		".io-wide #masthead-positioner": {
            "position": "absolute",
            "top": window.innerHeight + "px"
        },
        ".io-wide #masthead-positioner-height-offset, .io-wide .skip-nav": {
			"display": "none"
		},
		".io-wide #player": {
			"height": window.innerHeight + "px"
		},
		".io-wide .player-height": {
			"width": "100%",
			"height": "100%",
            "top": "0",
			"left": "-50%"
		},
		".io-wide .html5-video-container": {
			"height": "100%"
		},
		".io-wide .html5-main-video": {
			"width": "100%",
			"height": "100%",
			"top": "0",
			"left": "0"
		},
		".io-wide .ytp-chrome-bottom": {
			"width": "100%",
			"left": "0"
		},
        ".io-wide #content": {
            "margin-top": "60px"
        }
	});
})();