<!DOCTYPE HTML> <html> <head> <script> function tweak() { // div with style "border: 10px solid green" var shadowDiv = document.createElement("div"); shadowDiv.style.border = "10px solid green"; // Insertion point will match nothing and use fallback content. var insertionPoint = document.createElement("content"); shadowDiv.appendChild(insertionPoint); // Append three nodes as children to use as fallback content. insertionPoint.innerHTML = '<span style="background-color: orange">Hello</span> <span style="background-color: green">World</span>'; var shadowRoot = document.getElementById('outer').createShadowRoot(); shadowRoot.appendChild(shadowDiv); } </script> </head> <body onload="tweak()"> <div id="outer"></div> </body> </html>