Userscript that hides the YouTube header when a video is playing

headerhider.user.js

// ==UserScript==
// @version     6
// @name        Hide YouTube Header
// @namespace   https://github.com/YePpHa/YouTubeCenter/issues/786
// @description Hides YouTube header when a video is playing
// @match       *://www.youtube.com/*
// @run-at      document-start
// @grant       none
// @noframes
// ==/UserScript==
(function () {
    'use strict';
    var sheet =
        '#masthead-positioner,#masthead-positioner-height-offset{max-height:90px;transition:max-height 1s;overflow:hidden}\n' +
        '#body #body-container .hide{max-height:0 !important;}',
        core = function () {
            var detour = window.onYouTubePlayerReady;
            function playerReady(a) {
                var header = document.getElementById('masthead-positioner'),
                    offset = document.getElementById('masthead-positioner-height-offset');
                function stateChange(b) {
                    if (!/0|2|5/.test(b) && !header.classList.contains('hide') && location.href.indexOf('/watch') !== -1) {
                        header.classList.add('hide');
                        offset.classList.add('hide');
                    } else if (/0|2|5/.test(b) && header.classList.contains('hide')) {
                        header.classList.remove('hide');
                        offset.classList.remove('hide');
                    }
                }
                if (location.href.indexOf('/watch') !== -1) {
                    header.classList.add('hide');
                    offset.classList.add('hide');
                }
                a.addEventListener('onStateChange', stateChange, false);
            }
            window.onYouTubePlayerReady = function (){
                playerReady(arguments[0]);
                detour.apply(window, arguments);
            };
        };
    function inject(a, b) {
        var injection = document.createElement(b);
        document.head.appendChild(injection);
        injection.textContent = a;
    }
    inject(sheet, 'style');
    inject('(' + core + ')()', 'script');
}());

Could you do in this script or in other, that when you push or switch to Theater mode all upper head (options, YT logo, search, mic, create, notification, account - this line) is sliding up? Move mouse upper area - it's sliding down, but up high video.