If you take a look at the source[0], you&#x27;ll notice they roll their own viewport renderer, presumably as a way for them to do their &quot;tracking pixels&quot;. I imagine this might be what causes the difference in behavior? If anyone more knowledgeable could jump in, that would be cool.<p>[0] <a href="https:&#x2F;&#x2F;github.com&#x2F;ampproject&#x2F;amphtml&#x2F;blob&#x2F;master&#x2F;src&#x2F;viewport.js" rel="nofollow">https:&#x2F;&#x2F;github.com&#x2F;ampproject&#x2F;amphtml&#x2F;blob&#x2F;master&#x2F;src&#x2F;viewpo...</a>