Adaptive Modular Scale

A small javascript helper to get an adaptive modular scale font-size css string. It will interpolate between two modular scales and breakpoints and will return you sizes based on the given modular scales. This package is inspired by this tool by Florian Schulz.

yarn add adaptive-modular-scale
 
npm install adaptive-modular-scale

Usage

import styled from 'styled-components';
import adaptiveModularScale from 'adaptive-modular-scale';
 
const Headline = styled.h1`
  ${adaptiveModularScale(3, {
    // Minimum and maximum base
    base: [14, 16],
    // Minimum and maximum ratio
    ratio: [1.2, 1.78],
    // Two screen widths to interpolate between
    width: [320, 960],
    // Number of breakpoints between two widths
    breakpoints?: 8,
    // Optional corrections for steps
    corrections?: {
      // Correct minimal and maximum size for step. The below example
      // will correct the minimal step by -1px and the maximum step by +2px
      3: [-1, 2]
    },
    lineHeights?: {
      // Add minimal and maximum lineHeights for step.
      3: [1.2, 1.5]
    }
  })}
`;

The above example will return the following css.

.sc-bZQynM {
  font-size: 1.45rem;
  line-height: 1.2;
 
  @media (min-width: 25rem) {
    font-size: 1.989rem;
    line-height: 1.2375;
  }
  @media (min-width: 30rem) {
    font-size: 2.528rem;
    line-height: 1.275;
  }
  @media (min-width: 35rem) {
    font-size: 3.068rem;
    line-height: 1.3125;
  }
  @media (min-width: 40rem) {
    font-size: 3.607rem;
    line-height: 1.35;
  }
  @media (min-width: 45rem) {
    font-size: 4.147rem;
    line-height: 1.3875;
  }
  @media (min-width: 50rem) {
    font-size: 4.686rem;
    line-height: 1.425;
  }
  @media (min-width: 55rem) {
    font-size: 5.225rem;
    line-height: 1.4625;
  }
  @media (min-width: 60rem) {
    font-size: 5.765rem;
    line-height: 1.5;
  }
}

ThemeProvider

You can also add an adaptiveModularScale key to the theme object of your ThemeProvider.

Example

import styled, { ThemeProvider } from 'styled-components';
import adaptiveModularScale from 'adaptive-modular-scale';
 
const theme = {
  adaptiveModularScale: {
    base: [14, 16],
    ratio: [1.2, 1.78],
    width: [320, 960],
    breakpoints: 8
  }
};
 
// If you added the modular scale values to the ThemeProvider
// you dont have to pass it down every time
const Headline = styled.h1`
  ${adaptiveModularScale(5)}
`;
 
const App = () => (
  <ThemeProvider theme={theme}>
    <Headline>An adaptive modular scale sized headline</Headline>
  </ThemeProvider>
);

Custom css property

By default adaptive-modular-scale uses font-size as the css property. But you can also change the property by adding a property key to your config object.

Example

import styled, { ThemeProvider } from 'styled-components';
import adaptiveModularScale from 'adaptive-modular-scale';
 
const Headline = styled.h1`
  ${adaptiveModularScale(5, { property: 'margin-bottom' })}
`;

Options

step

number | required

The step on the modular scale

config

object | required

config.base

[number, number] | required

Array of minimum and maximum base size of modular scale.

config.ratio

[number, number] | required

Array of minimum and maximum ratio of modular scale.

config.width

[number, number] | required

Array of two screen widths in px. Between these values the modular scale will interpolate between both scales based on screen width.

config.breakpoints

number | required

Number of breakpoints between the two given screen widths which will be rendered to the css string.

config.corrections

{ [step]: [number, number] } | optional

Add optional corrections array with steps as keys.

const corrections = {
  // This will correct the minimal size of step "0" by -2px
  // and the maximum size by +1px
  0: [-2, 1]
};

config.lineHeights

{ [step]: [number, number] } | optional

Add optional lineHeights array with steps as keys.

config.property

string | optional | default: "font-size"

Add optional css property if you want to use adaptive modular scale for another property than font-size.

Additional methods

adaptive-modular-scale also exports a default modular scale method.

import styled from 'styled-components';
import { modularScale } from 'adaptive-modular-scale';
 
const base = 16;
const ratio = 1.6;
 
const Headline = styled.h1`
  font-size: ${modularScale(5, base, ratio)}px;
`;