111.js

const rootNode = document.getRootNode();
const htmlElementNode = rootNode.childNodes[0];
// console.log(htmlElementNode.childNodes); NodeList(3)[head, text, body]
const headElementNode = htmlElementNode.childNodes[0];
const textNode1 = htmlElementNode.childNodes[1];
const bodyElementNode = htmlElementNode.childNodes[2];
console.log(headElementNode.childNodes);
// sibling relation 
const h1 = document.querySelector("h1");
// const body = h1.parentNode.parentNode;
// body.style.color = "#efefef";
// body.style.backgroundColor = "#333"
const body = document.body
body.style.color = "#efefef";
body.style.backgroundColor = "#333"
const head = document.querySelector("head");
console.log(head);
const title = head.querySelector("title");
console.log(title.childNodes);
const container = document.querySelector(".container");
console.log(container.children);