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πŸ₯œ goober, a less than 1KB css-in-js solution.

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πŸͺ’ The Great Shave Off Challenge

Can you shave off bytes from goober? Do it and you're gonna get paid! More info here


I've always wondered if you could get a working solution for css-in-js with a smaller footprint. While I was working on a side project I wanted to use styled-components, or more accurately the styled pattern. Looking at the JavaScript bundle sizes, I quickly realized that I would have to include ~12kB(styled-components) or ~11kB(emotion) just so I can use the styled paradigm. So, I embarked on a mission to create a smaller alternative for these well established APIs.

Why the peanuts emoji?

It's a pun on the tagline.

css-in-js at the cost of peanuts! πŸ₯œgoober

Table of contents


The API is inspired by emotion styled function. Meaning, you call it with your tagName, and it returns a vDOM component for that tag. Note, setup needs to be ran before the styled function is used.

import { h } from 'preact';
import { styled, setup } from 'goober';

// Should be called here, and just once

const Icon = styled('span')`
    display: flex;
    flex: 1;
    color: red;

const Button = styled('button')`
    background: dodgerblue;
    color: white;
    border: ${Math.random()}px solid white;

    &:hover {
        padding: 1em;

    .otherClass {
        margin: 0;

    ${Icon} {
        color: black;


Comparison and tradeoffs

In this section I would like to compare goober, as objectively as I can, with the latest versions of two most well known css-in-js packages: styled-components and emotion.

I've used the following markers to reflect the state of each feature:

  • βœ… Supported
  • 🟑 Partially supported
  • πŸ›‘ Not supported

Here we go:

Feature name Goober Styled Components Emotion
Base bundle size 1.25 kB 12.6 kB 7.4 kB
Framework agnostic βœ… πŸ›‘ πŸ›‘
Render with target *1 βœ… πŸ›‘ πŸ›‘
css api βœ… βœ… βœ…
css prop βœ… βœ… βœ…
styled βœ… βœ… βœ…
styled.<tag> βœ… *2 βœ… βœ…
as βœ… βœ… βœ…
.withComponent πŸ›‘ βœ… βœ…
.attrs πŸ›‘ βœ… πŸ›‘
shouldForwardProp βœ… βœ… βœ…
keyframes βœ… βœ… βœ…
Labels πŸ›‘ πŸ›‘ βœ…
ClassNames πŸ›‘ πŸ›‘ βœ…
Global styles βœ… βœ… βœ…
SSR βœ… βœ… βœ…
Theming βœ… βœ… βœ…
Tagged Templates βœ… βœ… βœ…
Object styles βœ… βœ… βœ…
Dynamic styles βœ… βœ… βœ…


  • [1] goober can render in any dom target. Meaning you can use goober to define scoped styles in any context. Really useful for web-components.
  • [2] Supported only via babel-plugin-transform-goober


You can get the critical CSS for SSR via extractCss. Take a look at this example: CodeSandbox: SSR with Preact and goober and read the full explanation for extractCSS and targets below.


The results are included inside the build output as well.


Coming soon!


The benchmark is testing the following scenario:

import styled from '<packageName>';

// Create the dynamic styled component
const Foo = styled('div')((props) => ({
    opacity: props.counter > 0.5 ? 1 : 0,
    '@media (min-width: 1px)': {
        rule: 'all'
    '&:hover': {
        another: 1,
        display: 'space'

// Serialize the component
renderToString(<Foo counter={Math.random()} />);

The results are:

goober x 200,437 ops/sec Β±1.93% (87 runs sampled)
[email protected] x 12,650 ops/sec Β±9.09% (48 runs sampled)
[email protected] x 104,229 ops/sec Β±2.06% (88 runs sampled)

Fastest is: goober


As you can see, goober supports most of the CSS syntax. If you find any issues, please submit a ticket, or open a PR with a fix.

styled(tagName: String | Function, forwardRef?: Function)

  • @param {String|Function} tagName The name of the DOM element you'd like the styles to be applied to
  • @param {Function} forwardRef Forward ref function. Usually React.forwardRef
  • @returns {Function} Returns the tag template function.
import { styled } from 'goober';

const Btn = styled('button')`
    border-radius: 4px;

Different ways of customizing the styles

Tagged templates functions
import { styled } from 'goober';

const Btn = styled('button')`
    border-radius: ${(props) => props.size}px;

<Btn size={20} />;
Function that returns a string
import { styled } from 'goober';

const Btn = styled('button')(
    (props) => `
  border-radius: ${props.size}px;

<Btn size={20} />;
import { styled } from 'goober';

const Btn = styled('button')((props) => ({
    borderRadius: props.size + 'px'

<Btn size={20} />;
import { styled } from 'goober';

const Btn = styled('button')([
    { color: 'tomato' },
    ({ isPrimary }) => ({ background: isPrimary ? 'cyan' : 'gray' })

<Btn />; // This will render the `Button` with `background: gray;`
<Btn isPrimary />; // This will render the `Button` with `background: cyan;`
Forward ref function

As goober is JSX library agnostic, you need to pass in the forward ref function for the library you are using. Here's how you do it for React.

const Title = styled('h1', React.forwardRef)`
    font-weight: bold;
    color: dodgerblue;

setup(pragma: Function, prefixer?: Function, theme?: Function, forwardProps?: Function)

The call to setup() should occur only once. It should be called in the entry file of your project.

Given the fact that react uses createElement for the transformed elements and preact uses h, setup should be called with the proper pragma function. This was added to reduce the bundled size and being able to bundle an esmodule version. At the moment, it's the best tradeoff I can think of.

import React from 'react';
import { setup } from 'goober';


With prefixer

import React from 'react';
import { setup } from 'goober';

const customPrefixer = (key, value) => `${key}: ${value};\n`;

setup(React.createElement, customPrefixer);

With theme

import React, { createContext, useContext, createElement } from 'react';
import { setup, styled } from 'goober';

const theme = { primary: 'blue' };
const ThemeContext = createContext(theme);
const useTheme = () => useContext(ThemeContext);

setup(createElement, undefined, useTheme);

const ContainerWithTheme = styled('div')`
    color: ${(props) => props.theme.primary};

With forwardProps

The forwardProps function offers a way to achieve the same shouldForwardProps functionality as emotion and styled-components (with transient props) offer. The difference here is that the function receives the whole props and you are in charge of removing the props that should not end up in the DOM.

This is a super useful functionality when paired with theme object, variants, or any other customisation one might need.

import React from 'react';
import { setup, styled } from 'goober';

setup(React.createElement, undefined, undefined, (props) => {
    for (let prop in props) {
        // Or any other conditions.
        // This could also check if this is a dev build and not remove the props
        if (prop === 'size') {
            delete props[prop];

The functionality of "transient props" (with a "$" prefix) can be implemented as follows:

import React from 'react';
import { setup, styled } from 'goober';

setup(React.createElement, undefined, undefined, (props) => {
    for (let prop in props) {
        if (prop[0] === '$') {
            delete props[prop];

Alternatively you can use goober/should-forward-prop addon to pass only the filter function and not have to deal with the full props object.

import React from 'react';
import { setup, styled } from 'goober';
import { shouldForwardProp } from 'goober/should-forward-prop';

    // This package accepts a `filter` function. If you return false that prop
    // won't be included in the forwarded props.
    shouldForwardProp((prop) => {
        return prop !== 'size';


  • @returns {String} Returns the className.

To create a className, you need to call css with your style rules in a tagged template.

import { css } from "goober";

const BtnClassName = css`
  border-radius: 4px;

// vanilla JS
const btn = document.querySelector("#btn");
// BtnClassName === 'g016232'

// JSX
// BtnClassName === 'g016232'
const App => <button className={BtnClassName}>click</button>

Different ways of customizing css

Passing props to css tagged templates
import { css } from 'goober';

// JSX
const CustomButton = (props) => (
            border-radius: ${props.size}px;
Using css with JSON/Object
import { css } from 'goober';
const BtnClassName = (props) =>
        background: props.color,
        borderRadius: props.radius + 'px'

Notice: using css with object can reduce your bundle size.

We can also declare styles at the top of the file by wrapping css into a function that we call to get the className.

import { css } from 'goober';

const BtnClassName = (props) => css`
    border-radius: ${props.size}px;

// vanilla JS
// BtnClassName({size:20}) -> g016360
const btn = document.querySelector('#btn');
btn.classList.add(BtnClassName({ size: 20 }));

// JSX
// BtnClassName({size:20}) -> g016360
const App = () => <button className={BtnClassName({ size: 20 })}>click</button>;

The difference between calling css directly and wrapping into a function is the timing of its execution. The former is when the component(file) is imported, the latter is when it is actually rendered.

If you use extractCSS for SSR, you may prefer to use the latter, or the styled API to avoid inconsistent results.


By default, goober will append a style tag to the <head> of a document. You might want to target a different node, for instance, when you want to use goober with web components (so you'd want it to append style tags to individual shadowRoots). For this purpose, you can .bind a new target to the styled and css methods:

import * as goober from 'goober';
const target = document.getElementById('target');
const css = goober.css.bind({ target: target });
const styled = goober.styled.bind({ target: target });

If you don't provide a target, goober always defaults to <head> and in environments without a DOM (think certain SSR solutions), it will just use a plain string cache to store generated styles which you can extract with extractCSS(see below).


  • @returns {String}

Returns the <style> tag that is rendered in a target and clears the style sheet. Defaults to <head>.

const { extractCss } = require('goober');

// After your app has rendered, just call it:
const styleTag = `<style id="_goober">${extractCss()}</style>`;

// Note: To be able to `hydrate` the styles you should use the proper `id` so `goober` can pick it up and use it as the target from now on


To define your global styles you need to create a GlobalStyles component and use it as part of your tree. The createGlobalStyles is available at goober/global addon.

import { createGlobalStyles } from 'goober/global';

const GlobalStyles = createGlobalStyles`
  body {
    background: light;

  * {
    box-sizing: border-box;

export default function App() {
    return (
        <div id="root">
            <GlobalStyles />

How about using glob function directly?

Before the global addon, goober/global, there was a method named glob that was part of the main package that would do the same thing, more or less. Having only that method to define global styles usually led to missing global styles from the extracted css, since the pattern did not enforce the evaluation of the styles at render time. The glob method is still exported from goober/global, in case you have a hard dependency on it. It still has the same API:

import { glob } from 'goober';

  body {
    background: light;

  * {
    box-sizing: border-box;


keyframes is a helpful method to define reusable animations that can be decoupled from the main style declaration and shared across components.

import { keyframes } from 'goober';

const rotate = keyframes`
    from, to {
        transform: rotate(0deg);

    50% {
        transform: rotate(180deg);

const Wicked = styled('div')`
    background: tomato;
    color: white;
    animation: ${rotate} 1s ease-in-out;


To implement the shouldForwardProp without the need to provide the full loop over props you can use the goober/should-forward-prop addon.

import { h } from 'preact';
import { setup } from 'goober';
import { shouldForwardProp } from 'goober/should-forward-prop';

    shouldForwardProp((prop) => {
        // Do NOT forward props that start with `$` symbol
        return prop['0'] !== '$';


Babel plugin

You're in love with the styled.div syntax? Fear no more! We got you covered with a babel plugin that will take your lovely syntax from styled.tag and translate it to goober's styled("tag") call.

npm i --save-dev babel-plugin-transform-goober
# or
yarn add --dev babel-plugin-transform-goober

Visit the package in here for more info (

Babel macro plugin

A babel-plugin-macros macro for [πŸ₯œgoober][goober], rewriting styled.div syntax to styled('div') calls.


Once you've configured babel-plugin-macros, change your imports from goober to goober/macro.

Now you can create your components using styled.* syntax:.

import { styled } from 'goober/macro';

const Button = styled.button`
    margin: 0;
    padding: 1rem;
    font-size: 1rem;
    background-color: tomato;


Want to use goober with Next.js? We've got you covered! Follow the example below or from the main examples directory.

npx create-next-app --example with-goober with-goober-app
# or
yarn create next-app --example with-goober with-goober-app


Want to use goober with Gatsby? We've got you covered! We have our own plugin to deal with styling your Gatsby projects.

npm i --save goober gatsby-plugin-goober
# or
yarn add goober gatsby-plugin-goober

Preact CLI plugin

If you use Goober with Preact CLI, you can use preact-cli-goober-ssr

npm i --save-dev preact-cli-goober-ssr
# or
yarn add --dev preact-cli-goober-ssr

# preact.config.js
const gooberPlugin = require('preact-cli-goober-ssr')

export default (config, env) => {
  gooberPlugin(config, env)

When you build your Preact application, this will run extractCss on your pre-rendered pages and add critical styles for each page.

CSS Prop

You can use a custom css prop to pass in styles on HTML elements with this Babel plugin.


npm install --save-dev @agney/babel-plugin-goober-css-prop

List the plugin in .babelrc:

  "plugins": [


        display: flex;
        min-height: 100vh;
        justify-content: center;
        align-items: center;
    <h1 css="color: dodgerblue">Goober</h1>


  • [x] Basic CSS parsing
  • [x] Nested rules with pseudo selectors
  • [x] Nested styled components
  • [x] Extending Styles
  • [x] Media queries (@media)
  • [x] Keyframes (@keyframes)
  • [x] Smart (lazy) client-side hydration
  • [x] Styling any component
    • via const Btn = ({className}) => {...}; const TomatoBtn = styled(Btn)`color: tomato;`
  • [x] Vanilla (via css function)
  • [x] globalStyle (via glob) so one would be able to create global styles
  • [x] target/extract from elements other than <head>
  • [x] vendor prefixing

Sharing style

There are a couple of ways to effectively share/extend styles across components.


You can extend the desired component that needs to be enriched or overwritten with another set of css rules.

import { styled } from 'goober';

// Let's declare a primitive for our styled component
const Primitive = styled('span')`
    margin: 0;
    padding: 0;

// Later on we could get the primitive shared styles and also add our owns
const Container = styled(Primitive)`
    padding: 1em;

Using as prop

Another helpful way to extend a certain component is with the as property. Given our example above we could modify it like:

import { styled } from 'goober';

// Our primitive element
const Primitive = styled('span')`
    margin: 0;
    padding: 0;

const Container = styled('div')`
    padding: 1em;

// At composition/render time
<Primitive as={'div'} /> // <div class="go01234" />

// Or using the `Container`
<Primitive as={Container} /> // <div class="go01234 go56789" />


Autoprefixing is a helpful way to make sure the generated css will work seamlessly on the whole spectrum of browsers. With that in mind, the core goober package can't hold that logic to determine the autoprefixing needs, so we added a new package that you can choose to address them.

npm install goober
# or
yarn add goober

After the main package is installed it's time to bootstrap goober with it:

import { setup } from 'goober';
import { prefix } from 'goober/prefixer';

// Bootstrap goober
setup(React.createElement, prefix);

And voilΓ ! It is done!


goober comes with type definitions build in, making it easy to get started in TypeScript straight away.

Prop Types

If you're using custom props and wish to style based on them, you can do so as follows:

interface Props {
    size: number;

    border-radius: ${(props) => props.size}px;

// This also works!

    border-radius: ${(props) => props.size}px;

Extending Theme

If you're using a custom theme and want to add types to it, you can create a declaration file at the base of your project.

// goober.d.t.s

import 'goober';

declare module 'goober' {
    export interface DefaultTheme {
        colors: {
            primary: string;

You should now have autocompletion for your theme.

const ThemeContainer = styled('div')`
    background-color: ${(props) => props.theme.colors.primary};

Browser support

goober supports all major browsers (Chrome, Edge, Firefox, Safari).

To support IE 11 and older browsers, make sure to use a tool like Babel to transform your code into code that works in the browsers you target.


Feel free to try it out and checkout the examples. If you wanna fix something feel free to open a issue or a PR.


Thank you to all our backers! πŸ™


Support this project by becoming a sponsor. Your logo will show up here with a link to your website.

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