&gt; <i>Firefox doesn&#x27;t natively support web components </i><p>FWIW, that&#x27;s because there hasn&#x27;t been a reasonably stable, agreed upon collection of specs for us to implement. Custom Element only reached multi-vendor agreement a few months ago (<a href="https:&#x2F;&#x2F;annevankesteren.nl&#x2F;2016&#x2F;02&#x2F;custom-elements-no-longer-contentious" rel="nofollow">https:&#x2F;&#x2F;annevankesteren.nl&#x2F;2016&#x2F;02&#x2F;custom-elements-no-longer...</a>).<p>Polymer is a useful library, but it only represents a single vendor&#x27;s vision, not any sort of standardized specification.