XML > HTML! (OK. There's some CSS as well!) Write a well-formed XML (eXtensible Markup Language) document containing your data
XML was first standardised 25 years ago in 1998. It is a way to structure documents in a (mostly) human readable format while making them easy(ish) to interpret by machines. XML has several schemas - which are standard ways of defining a document - but you are free to structure it however you like.
fa fa-rocket Create an XSL (eXtensible Style Sheet) to describe how to render it
XSL is quite a bit different from HTML's CSS (Cascading Style Sheets). An XSL document defines how XML should be rendered by the browser. It can contain a mixture of (X)HTML, CSS, JavaScript, and any other web technologies.
fa fa-paint-brush Use XSLT (XSL Transformations) to extract data from the XML and render it
XSLT is a special set of instructions which tells the browser how to parse the XML. It can incorporate multiple templates to allow for complex interactions with the source data.
fa fa-cogs Understand how XPATH (XML Path Language) can interrogate your XML
XPath is a query language. It provides a syntax for finding specific parts of an XML document
fa fa-question-circle Is this a good idea?

No!

This is a silly idea and should in no way be used for anything sensible.

One of the reasons XML (and XHTML) fell out of favour is that they are unforgiving. Miss a /? Your site is broken. Forget to close an element? Your site is broken. Incorrectly escape something? Your site is broken. Mismatched elements? Your site is broken.

HTML, by contrast, is rendered by engines which are tolerant. Made a mistake in your HTML? The browser will do its best to display the page.

One area where XML and XSL shine is if you are working with highly structured and regular data and want to display it in a more human-friendly way.

But, nowadays, there's very little reason to use XML for display purposes. Unless you want to get frustrated.

 Background information: I was inspired by "HTML is all you need to make a website." I previously created "YOU DON'T NEED HTML!" <![CDATA[You can learn more about XML at the W3C.]]> About the author: <![CDATA[Visit my (HTML) website to learn more about this page]]> <![CDATA[Contact @edent]]>