Shadow Dom

window.onload = function () {
  let oBody = document.querySelector("body");
  let oDiv = document.createElement("div");
  oDiv.innerHTML =
    "<style>div{height: 200px;width: 200px;background: red;}</style><div>hello</div>";

  const { innerHTML } = oDiv;
  oDiv.innerHTML = "";
  const shadow = oDiv.attachShadow({ mode: "closed" });
  shadow.innerHTML = innerHTML;

  console.log(shadow);
  oBody.appendChild(oDiv);
};