This is where most of the 'logic' breaks down for me. The specificity scoring is a system of weights that trips up a lot of new front end developers. It's not straightforward. Different selectors have different weights you need to know about. There are 'hacks' you need to know about when you find yourself needing to override particularly heavy selectors. https://developer.mozilla.org/en-US/docs/Web/CSS/Specificity
And conveniently the author doesn't mention !important.
I think nowadays I find myself using CSS variables and calc() more often to establish some system of logic in my CSS. I can have --spacing: 120% variable at the root of the tree, and all its descendants can consume that and use calc() to multiply that by a unit value to have consistently scaled spacing. The author doesn't mention this, but it's great!