HTML in embed-page is presented as DIV

[sashafirsov]

Which leads as to CSS overlap as to mediaqueries mess-up.
https://jsfiddle.net/juL054e3/

[sashafirsov]

DOM and CSS scoping by shadowDOM most likely would not permit the HTML inside of EMBED-PAGE( to be verified ). If so the solution would require custom anonymous element to mimic HTML tag API and CSS pre-processing.