CSS

A stylesheet linked from index.html is built, not copied: @imports are inlined, url()s are rewritten to files in the output, and release builds minify. There is nothing to configure and no PostCSS pipeline to maintain.

<link rel="stylesheet" href="./src/styles.css" />

The same pipeline applies however a stylesheet reaches the build — linked from a document, imported from a module (import "./button.css"), a CSS Module, or named as an entry — and to what a test imports under esdev test.

Bundling

@import inlines the named stylesheet, resolved the way the build resolves everything else. A url() naming a local file copies it into dist/assets/ under a content-hashed name and points the URL at the copy:

.icon {
  background: url("./icon.svg"); /* dist/assets/icon-a1b2c3.svg */
}

Pass --css-urls=inline to inline those files as data: URLs instead. A library target takes the same choice as a "css-urls" option.

CSS Modules

A .module.css file is scoped: each class becomes a name only that stylesheet uses, and the JavaScript import receives the map.

/* button.module.css */
.btn {
  padding: 0.5rem 1rem;
}

import styles from "./button.module.css";

button.className = styles.btn; // "btn_c2e58308"

A composed module is @imported from the scoped sheet it builds on, and url()s inside a module stay relative to it.

Minification

esdev build --minify minifies stylesheets alongside everything else. The pass is deliberately value-level — six-digit colours, zero dimensions outside math, repeated shorthand sides, overridden adjacent declarations — spellings that are safe without knowing every property's grammar. What the parser does not understand it leaves byte-identical: print(parse(x)) round-trips any input, valid or not.

No syntax lowering and no vendor prefixing: nesting, color-mix() and logical properties ship to browsers that support them, so lowering today would only enlarge the file.

Tailwind CSS

A stylesheet that imports tailwindcss or uses its directives is compiled by the project's own tailwindcss, with nothing to configure:

@import "tailwindcss";

See Tailwind CSS for directives, @plugin (CommonJS ones included), and why v3 is refused.

Stylesheets from a plugin

A plugin hands esdev CSS by returning { code, type: "css" } for any extension — a Sass plugin compiling Card.module.scss, for example. The result is bundled, scoped and linked like a stylesheet that was written by hand. See Plugins.

Libraries ship their stylesheets

A --lib build keeps an imported stylesheet beside the module that imports it (import "./button.css" emits no stub and ships the sheet), and a .module.css ships scoped. When the package's exports cannot reach a copied stylesheet, the build warns and names the line to add — esdev never edits package.json itself.