// ==UserScript==
// @name         Fullscreen Button
// @match  *://*/*
// @version      0.1
// @description A simple float button for entering fullscreen.
// @noframes
// @license CC0
// @namespace https://greasyfork.org/users/123506
// @downloadURL none
// ==/UserScript==
'use strict';
document.body.insertAdjacentHTML("afterbegin",'<div id="b0n" style="background-color: rgb(209, 209, 209);position: fixed;display: flex;opacity: 0.66;margin: 1em;z-index: 2147483647" ><svg width="24" height="24"><path d="M7,14L5,14v5h5v-2L7,17v-3zM5,10h2L7,7h3L10,5L5,5v5zM17,17h-3v2h5v-5h-2v3zM14,5v2h3v3h2L19,5h-5z"/></svg></div>');
var btn=document.getElementById("b0n");
var action=function(){
    document.documentElement.requestFullscreen();
    document.documentElement.webkitRequestFullscreen();
    btn.remove();
}
btn.onclick=action;