Let’s not beat around the bush: writing great CSS code can be painful.
A lot of developers don’t want to do CSS development. I can do everything you want, but nah! No CSS.
When I was building apps, CSS was the part I never enjoyed. But you can’t escape it, right? I mean, we are so focused on the user experience and the design nowadays that we just can’t skip that part.
When beginning a project, all is working fine. You have a few CSS selectors : .title input #app, easy peasy.
But when your app gets bigger and bigger, it starts to look awful. You’re confused about your CSS selectors. You find yourself writing things like div#app .list li.item a. You keep writing the same code over and over again. You throw all your code at the end of your file because you just don’t care, CSS sucks. And there you go: 500 lines of CSS completely unmaintainable.