<!DOCTYPE HTML> <html> <head> <script> function tweak() { var oldestShadow = document.getElementById('outer').createShadowRoot(); oldestShadow.innerHTML = 'Hello'; var olderShadow = document.getElementById('outer').createShadowRoot(); var youngerShadow = document.getElementById('outer').createShadowRoot(); youngerShadow.innerHTML = '<div style="background-color:green"><shadow></shadow></div>'; olderShadow.innerHTML = '<shadow></shadow> World'; } </script> </head> <body onload="tweak()"> <div id="outer"> <div style="width:300px; height:100px; background-color:red;"></div> </div> </body> </html>