@decantr/css

@decantr/css

Support status: supported-secondary Release channel: stable

Legacy optional CSS atoms runtime for Decantr projects that explicitly adopt the Decantr CSS adapter.

Decantr 3.8.1 defaults to contract-only governance. New greenfield and Brownfield projects should not install @decantr/css unless --adoption=decantr-css is explicit or an existing project already depends on this runtime.

Installation

npm install @decantr/css

Usage

import { css } from '@decantr/css';

// In your components
<div className={css('_flex _col _gap4 _p4')}>
  <h1 className={css('_heading1')}>Title</h1>
  <p className={css('_textsm _fgmuted')}>Description</p>
</div>

How It Works

The css() function:

• Parses atom strings (e.g., '_flex _col _gap4')
• Resolves each atom to CSS (e.g., _flex -> display:flex)
• Injects the CSS into the DOM via <style> tags
• Returns the class names for use in your markup

CSS is injected into @layer d.atoms for proper cascade control.

API

css(...classes)

Process atom strings and inject CSS. Returns space-separated class names.

css('_flex _col')  // Returns: '_flex _col', injects CSS
css('_flex', '_col', condition && '_gap4')  // Handles multiple args, falsy values

define(name, declaration)

Register a custom atom.

define('_brand', 'color:var(--brand);font-weight:700');
css('_brand')  // Now works

extractCSS()

Get all injected CSS as a string (for SSR).

const cssString = extractCSS();
// Returns: '@layer d.atoms{._flex{display:flex}...}'

reset()

Clear all injected styles (for testing).

reset();

Atom Reference

Display

_flex, _grid, _block, _inline, _none, _contents

Flexbox

_col, _row, _wrap, _nowrap, _flex1, _grow, _shrink0

Alignment

_aic (align-items:center), _jcc (justify-content:center), _jcsb (space-between)

Spacing

_gap{n}, _p{n}, _m{n}, _pt{n}, _px{n}, _my{n} where n = 0-96

Sizing

_wfull, _hfull, _w{n}, _h{n}, _minw0, _maxwfull

Typography

_textsm, _textlg, _text2xl, _heading1-_heading6, _fontbold

Colors (use CSS variables)

_bgprimary, _bgsurface, _fgmuted, _bcborder

Responsive Prefixes

Mobile-first breakpoints: _sm: (640px), _md: (768px), _lg: (1024px), _xl: (1280px)

<div className={css('_gc1 _sm:gc2 _lg:gc4')}>
  {/* 1 col -> 2 cols at 640px -> 4 cols at 1024px */}
</div>

Pseudo-class Prefixes

_h: (hover), _f: (focus), _fv: (focus-visible), _a: (active)

<button className={css('_bgprimary _h:bgprimary/80')}>
  Hover me
</button>

Opacity Modifiers

_bgprimary/50 -> 50% opacity via color-mix()

Arbitrary Values

_w[512px], _p[clamp(1rem,3vw,2rem)], _bg[#1a1a2e]

Integration with Decantr

When you explicitly scaffold a project with @decantr/cli --adoption=decantr-css, it generates:

• src/styles/tokens.css - Theme tokens (colors, spacing, radii)
• src/styles/treatments.css - Visual treatment classes (interactive, surface, data, control, section, annotation)
• src/styles/decorators.css - Optional decorator classes

Import these alongside @decantr/css:

import { css } from '@decantr/css';
import './styles/tokens.css';
import './styles/treatments.css';
import './styles/decorators.css';

Security And Permissions

@decantr/css is a CSS atom runtime. It does not inspect projects, read or write files, call the network, spawn processes, emit telemetry, or upload source. See security permissions.

License

MIT