My web app generate an amp-valid page and via https://validator.ampproject.org/# I can check that the output is amp- valid.
But for me is not enough I want somehow to render visualy the <amp-*></amp-*> elements. I mean if I want to chance some css for these elements how I can do it without deploying my application all over the time?
Some elements may not be rendered because they need the correct amp extention in order to load. Therefore if some elements do not get rendered just load the correct amp.js extention in order to get rendered into your browser.
Furthermore make sure that the AMP javascript and their plugis get loaded firtst in order to be able to correcly get rendered.