About HTML imports
Table of contents
Why HTML Imports?
HTML Imports let you include and reuse HTML documents in other HTML documents,
just as <script> tags let you include external Javascript in their pages.
In particular, imports let you include
custom element definitions from external URLs.
Basic usage
For HTML imports use the import relation on a standard <link> tag, for example:
<link rel="import" href="my-custom-element.html">