What you discover about CSS is that it's an accretive thing. You start out perhaps with a (comparatively) simple basis, whatever came with whatever app or fram

What you discover about CSS is that it's an accretive thing. You start out perhaps with a (comparatively) simple basis, whatever came with whatever app or framework your site is based on, or if you're lucky and starting from scratch, what you yourself wrote and understand. Then over the years, you and other developers and designers on the team add to the CSS. You can't go back and change anything, because changing something to look right on this page may make it look wrong on another page. You can easily see the structure of selectors on the page you're looking at, but not the set of all possible selector structures on every possible potential page on the site to know how it will cascade everywhere. So you just add on, gradually getting more and more specific with the selectors up to the point where you have to start using !importants. Meanwhile, over the years, the 'best practices' change, and the CSS that you and your coworkers write changes to adapt. So you end up with things originally sized in pixels, later multiplied by a floating point scaling, overridden with em measurements, overridden by whatever the current fad in measurements is. Change any of that and it breaks random things throughout the site due to cascading, inheritance, and document structure/selector specificity. Due to the way it accretes over time, you end up with massive amounts of CSS, most of which is overridden but can't be removed without breaking random things. You can't reconcile it or do it the right way without a full rewrite. And in the end, it still always takes a few hours to figure out how to center something without breaking the alignment of other things, or whatever you're trying to do. Because it will be different than it was last time. It's not like just calling element.align(vertical=center, horizontal=center); as it would be in a programming language. It's a series of hacks built upon hacks to do the most basic things.