fuz_css

CSS with more utility 🪴

fuz_css is a semantic-first CSS framework and design system. Semantic HTML looks finished with zero classes: headings, links, buttons, forms, tables, and callouts come styled, and block elements space themselves. Themes are a handful of knobs, not a stylesheet: hues, intents, lightness curves, and scales re-derive every color and size in plain CSS, and the contrast, gamut, and ramp-order checks the shipped themes pass are an API you can run on your own. A Vite plugin generates one stylesheet holding only the variables, base styles, and utility classes your code uses, for Svelte, React, Preact, Solid, and plain HTML.

Browse the docs at css.fuz.dev, and try the theme editor. More about the stack at fuz.dev.

It's in early alpha with breaking changes ahead. Feedback and design input is welcome in the discussions.

Install

npm i -D @fuzdev/fuz_css

Usage

Add the Vite plugin:

// vite.config.ts
import {defineConfig} from 'vite';
import {sveltekit} from '@sveltejs/kit/vite';
import {vite_plugin_fuz_css} from '@fuzdev/fuz_css/vite_plugin_fuz_css.ts';

export default defineConfig({
    plugins: [sveltekit(), vite_plugin_fuz_css()],
});

Then import its virtual module once, from your root layout or entry file:

import 'virtual:fuz.css';

For JSX (React, Preact, Solid), install acorn-jsx and pass it as vite_plugin_fuz_css({acorn_plugins: [jsx()]}). The setup docs cover each framework and the TypeScript declaration for the virtual module.

Without a build step

The package's two plain stylesheets work in any page, the base style.css and theme.css with every variable. jsDelivr serves them from npm - pin a version:

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@fuzdev/fuz_css@VERSION/dist/theme.css" />
<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@fuzdev/fuz_css@VERSION/dist/style.css" />

That's the full semantic styling; utility classes and baked-in themes need the plugin.

Semantic first

This form looks finished, themed, and spaced with only a built-in convention class:

<form>
    <label>
        <div class="title">email</div>
        <input type="email" />
    </label>
    <button>subscribe</button>
</form>

The title class is one of the built-in conventions the base styles recognize, like selected and palette_c. When the defaults don't cover something, reach for a class:

<!-- composite, token, and literal classes -->
<div class="row gap_md justify-content:space-between">
    <button class="palette_c">delete</button>
    <button class="selected">saved</button>
</div>

Coming from Tailwind

• The root font size is 62.5%, so 1rem is 10px at the browser default and body text is 1.6rem. Every rem length on the page follows it, including third-party ones, which render at 62.5% of what their authors intended. Tailwind's p-4 is 1rem, 16px; here 16px is 1.6rem, and the spacing tokens carry the scale (p_xl is 16px at the defaults).
• Utilities are generated from what you use, found by parsing your source rather than matching it with a regex.
• Four class types: token classes map to design variables (p_md, color_a_50), keyword classes are CSS keywords that name their property (flex, sticky, uppercase), composites bundle properties (row, box, panel), and literals are CSS itself in property:value form (justify-content:center, margin:0~auto), with modifiers like md: and hover:.
• Tailwind's keyword names resolve, its own names don't: a Tailwind project's flex, hidden, or sticky gets the same CSS here, but items-center and justify-between generate nothing, with no warning, so flex items-center half-works. Spell those as literals (align-items:center).
• Tokens, keywords, and literals beat composites: composites render in a lower cascade layer, so panel shadow_md gets the medium shadow whatever the class order.

More in the classes docs.

Contributing

fuz.dev/contributing

License 🐦

0BSD