Also, this guy is calling HTML a programming language. Make of that what you will...

Web components = custom elements

:shrug:

  :root { --color: blue; }
  div { --color: green; }
  #alert { --color: red; }
  * { color: var(--color); }

  <p>I inherited blue from the root element!</p>
  <div>I got green set directly on me!</div>
  <div id='alert'>
    While I got red set directly on me!
    <p>I’m red too, because of inheritance!</p>
  </div>

It seems every object is given variables (--abc). And then there are global variables and local variables. I guess this is the "cascading" feature. var is a function computed at the time of instantiation. And refers to local variables first. Then looks at global variable. Inheritance comes from ?? The p tag seems it is not root so therefore it is not blue.

Having explained it, I think about it better, but this really messes up how I thought of CSS. CSS is where the second stanza overwrites the first stanza. Yet global and local variables really hurts my head. A few complex CSS files later, it is bound to be unusable to determine result without getting a computer program to help.