PostCSS
ELI5 — The Vibe Check
PostCSS is a CSS processor that does... whatever its plugins tell it to do. It's like an empty pipeline where you plug in transformations. Autoprefixer? PostCSS plugin. Tailwind? PostCSS plugin. It's the middleware of the CSS world.
Real Talk
PostCSS is a tool for transforming CSS with JavaScript plugins. It parses CSS into an AST, runs it through a plugin pipeline, and outputs transformed CSS. Popular plugins include Autoprefixer, cssnano for minification, and Tailwind CSS itself runs as a PostCSS plugin.
When You'll Hear This
"PostCSS isn't a preprocessor, it's a plugin runner" / "Tailwind is technically just a PostCSS plugin"
Related Terms
Atomic CSS
Atomic CSS is the idea that every CSS class should do exactly one thing. Instead of .card-header, you have .p-4 .font-bold .text-blue-500.
Autoprefixer
Autoprefixer is the robot that adds -webkit-, -moz-, and all those annoying vendor prefixes to your CSS so you don't have to.
CSS Nesting
CSS Nesting finally brings the one feature everyone used Sass for directly into plain CSS.