Background

换行
// ==UserScript==
// @name         Background
// @namespace    http://tampermonkey.net/
// @version      1.0
// @description  bg
// @author       umaimann
// @match        *://*/*
// @grant        none
// @license      MIT
// ==/UserScript==

(function() {
    'use strict';

    var existing = document.getElementById('custom-bg');
    if(existing){ existing.remove(); }

    // 背景用 div 作成
    var bg = document.createElement('div');
    bg.id = 'custom-bg';
    bg.style.position = 'fixed';
    bg.style.top = '0';
    bg.style.left = '0';
    bg.style.width = '100vw';
    bg.style.height = '100vh';
    bg.style.zIndex = '-1';
    bg.style.backgroundImage = "url('https://videotourl.com/images/1776643221632-ca2085be-e1f7-46d2-8a42-1470408bab73.jpeg')";
    bg.style.backgroundSize = 'cover';
    bg.style.backgroundRepeat = 'no-repeat';
    bg.style.backgroundPosition = 'center center';
    document.body.appendChild(bg);
})();