Context: Early web browsers supported only a very simple version of HTML. The rapid development of proprietary web browsers led to the development of non-standard dialects of HTML, leading to problems with interoperability. Modern web browsers support a combination of standards-based and de facto HTML and XHTML, which should be rendered in the same way by all browsers.

Question: Quick development of what kind of browsers led to non-standard HTML dialects?
Answer: proprietary web browsers

Question: Non-standard dialects led to what?
Answer: problems with interoperability

Question: Modern browser support standards-based and defacto what?
Answer: HTML and XHTML

Question: HTML and XHTML should be what by all browsers?
Answer: rendered in the same way

Question: What did early XHTML support?
Answer: Unanswerable

Question: What did the rapid development of modern web browsers lead to?
Answer: Unanswerable

Question: What problems arose after the development of modern web browsers?
Answer: Unanswerable

Question: How should non-standard dialects be treated by all browsers?
Answer: Unanswerable

Question: What are two things that a simple HTML version supports?
Answer: Unanswerable