An additional idea
Website page...
data:
URL page
for opening an offline Web Storage resource/page with JavaScript and .shadowRoot
host property...
that resource embedded into a shadow Document Object Model tree attached with a "template" element (node) with an attribute, this defined declaratively in the normal HTML DOM tree of the page
-
<div id="shadow-root-parent-host-element">
<template shadowrootmode="open">
<span>An element in shadow DOM tree, shadow set to open to display in the browser's visible page.</span>
</template>
</div>
(next)