What are the layers of website technology? [on hold]

Website design technology has evolved over the last 25 years, and has had to put up with a lot of nonsense with each new technology. I am aware of fundamental HTML and its evolutions, Javascript and how it allows dynamic content, CSS and its frankly bewildering set of seemingly not-very-well-thought-out options, the period where Macromedia Flash was a big thing, PHP and CGI server side scripts, and am aware of some of the almost code-free environments such as WordPress.

There are a lot of opinions of each, turning up noses at WordPress, thinking raw HTML is too old-school, the fact that different browsers did, still do and will continue to interpret the same code and render it differently. Responsiveness means different things to different developers, desktop pages are compromised on wide screens as a result.

What does the technology stack look like on a modern website?

Is there a level above which the weird browser incompatibilities are completely handled and standardised on, generic responsiveness layout rules are available, but not so far up the stack that you need WordPress and a pre-canned ‘theme’?