🎨 pico-css

A micro css preprocessor written in JS for JS. Under 100 lines. Supports nesting, mixins, parent selectors, and injectable values. Also comes with a tiny color manipulation utility.

install

npm install pico-css

usage

const css = require('pico-css');
const {lighten} = require('pico-css/chroma.js');

const btn = (color)=>{
  return css`
    cursor : pointer;
    background-color: ${color};
    &:hover{
      background-color: ${lighten(color, 0.2)};
    }
  `
}

css`
  body{
    margin-top : 20px;
    button{
      font-size : 2em;
      ${btn('#dabb1e')}
    }
  }
`;

// Converts to -->
`body{
  margin-top: 20px;
}
body button{
  font-size: 2em;
  cursor: pointer;
  background-color: #dabb1e;
}
body button:hover{
  background-color: #e1c84b;
}
`

why?

CSS preprocessors like Less and Sass, are very powerful, but require you to learn a new sub-language and any business logic would need to be duplicated between rendering and styling.

They also provide way more features then is typically needed, and can lead to weird footguns and overly designed style systems. pico-css is just a simple lib for convert nested css into valid css while leveraging JS for variables and logic.

chroma

pico-css also ships with a little color manipulation utility called chroma. Docs here.

const css = require('pico-css');
const {lighten, isDark, fade} = require('pico-css/chroma');


//Adaptive text color to ensure high contrast for readability
const textColor = (color)=>isDark(color) ? 'white' : 'black';

const btnColor = 'blue';

css`
button{
  color : ${textColor(btnColor)};
  background-color: ${btnColor}
  &:hover{
    background-color: ${lighten(btnColor, 0.2)};
  }
}`

features

pico-css comes with most of the useful features of css pre-processor with none of the bloat.

nesting

You can nest rules within rules

css`
  body{
    p{
      color : black;
    }
  }
`
//-->
`body p {
  color : black;
}`

parent selectors

The & operator represents the parent selectors of a nested rule and is most commonly used when applying a modifying class or pseudo-class to an existing selector.

css`
  p{
    &:hover{ color : blue; }
    &.selected{ color : red; }
  }`;

//-->
`p:hover{
  color : blue;
}
p.selected{
  color : red;
}`

mixins (aka no-root selector)

You can pass just rules to the parser and it will process them. This allows you to build mixins which can be used to copy repeated css, or create functions that return chunks of css.

const btn = (color)=>{
  return css`
    cursor : pointer;
    background-color: ${color};
    &:hover{
      background-color: ${lighten(color, 0.2)};
    }
  `
}

css`
  body{
    margin-top : 20px;
    button{
      font-size : 2em;
      ${btn('#dabb1e')}
    }
  }
`;

single line comments

Supports both block comments /* */ and single line comments //

api

css\style`` -> CSS String

The most common way to use pico-css is to use it as a tagged template literal. This will convert the template string and return valid a CSS string. You'll still need to save it, bundle it, or package it in some way, all pico-css cares about is parsing your styling.

const css = require('pico-css');
const {lighten} = require('pico-css/chroma.js');

const btn = (color)=>{
  return css`
    cursor : pointer;
    background-color: ${color};
    &:hover{
      background-color: ${lighten(color, 0.2)};
    }
  `
}

css`
  body{
    margin-top : 20px;
    button{
      font-size : 2em;
      ${btn('#dabb1e')}
    }
  }
`;

css.inject(styleObj) / css.inject\style` -> Style Tag

Converts and then creates a new <style> tag and injects it into the web document's head. Only works client side. Useufl for prototyping and experimenting.

const css = require('pico-css');

css.inject`
  body{
    background-color : red;
  }
`