The glaze from wintercounter

CSS-in-JS microlibrary for making design systems approachable with React

💡 Motivation

This project was born to combine the best of its predecessors into a single solution:

Utility-first CSS, as implemented by Tailwind CSS
- Fully static, but customizable upfront
- Embraces reusability with no duplicated rules
Constraint-based layouts, popularized by Theme UI
- Highly dynamic, thankfully to Emotion
- One-off styles can be defined naturally
Near-zero runtime, made possible by treat
- Theming support with legacy browsers in mind
- Static style extraction while retaining type safety

📚 Usage

Install the package and its peer dependencies:
```
npm install glaze treat
```

Define a theme, preferably by overriding the default tokens:

/* theme.treat.js */

import { createTheme, defaultTokens } from 'glaze';

export default createTheme({
  ...defaultTokens,

  // Customization
  scales: {
    ...defaultTokens.scales,
    color: {
      red: '#f8485e',
    },
  },
});

Keeping the runtime as small as possible, only a few tokens (breakpoints, shorthands and aliases) are embedded into production JavaScript bundles. Other values can only be accessed exclusively for styling, as shown later.

Apply the theme through ThemeProvider:

📝 The Gatsby plugin for glaze does this unobtrusively.

import { ThemeProvider } from 'glaze';
import theme from './theme.treat';

export default function Layout({ children }) {
  return <ThemeProvider theme={theme}>{children}</ThemeProvider>;
}

Style elements with the sx function:

import { useStyling } from 'glaze';

export default function Component() {
  const sx = useStyling();

  return (
    <p
      className={sx({
        px: 4, // Sets padding-left and padding-right to 1rem
        color: 'white',
        bg: 'red', // Sets background to #f8485e
      })}
    >
      Hello, world!
    </p>
  );
}

Set up static style extraction with the help of treat.

📝 The Gatsby plugin for treat does this unobtrusively.
- Afterwards, selector-based CSS rules may be created with globalStyle in *.treat.js files. They have to be applied as a side effect, e.g. from a top-level layout component:
```
import './globalStyles.treat.js';
```
Configure server-side rendering for dynamically created styles.

🤔 How it works

The sx function maps themed values to statically generated class names
- If that fails, the style gets injected dynamically through the CSSOM
Dynamic styles which are not in use by any component get removed

Rule handling

Transform each alias to its corresponding CSS property name or custom shorthand
Resolve values from the scales available
- CSS properties associated with a custom shorthand are resolved one by one

Example

Given the theme below:

import { createTheme } from 'glaze';

export default createTheme({
  scales: {
    spacing: { 4: '1rem' },
  },
  shorthands: {
    paddingX: ['paddingLeft', 'paddingRight'],
  },
  aliases: {
    px: 'paddingX',
  },
  matchers: {
    paddingLeft: 'spacing',
    paddingRight: 'spacing',
  },
});