Corner smoothing

Squircles for the web.

Supports filled squircles and border quircles. Supports React and vanilla js. Works for all components/HTML elements.

The corner smoothing is the same as the Figma corner smoothing through the use of figma-squircle.

The implementation uses clip-path, so user interactions such as hover follows the smooth corners.

Live demo.

React component

import { Squircle } from 'corner-smoothing'

    padding: '1rem 1.25rem',
    backgroundColor: '#7c3aed',
    color: '#fff',
    display: 'inline-block',
  Lorem ipsum

Squircle border

A squircle border is created by rendering two squircles on top of each other. The inner one being smaller and centered in the outer. The border is the region where the outer squircle is not covered by the inner squircle. The inner squircle is rendered with the ::before pseudo-element. The corner radius of the inner squircle is adjusted to follow the radius of the outer squircle to give the correct visuals.

All this happens automatically. You just need to know that the border color is defined by background-color and that actual background color is defined by background-color on the ::before pseudo-element. An added benefit of this is that the border can have a gradient.

import { Squircle } from 'corner-smoothing'
import styled from 'styled-components'

const StyledSquircle = styled.div`
  padding: 1rem 1.25rem;
  display: inline-block;

  /* Border color */
  background: linear-gradient(45deg, #7c3aed, #ff1b6b);

  ::before {
    /* Background color  */
    background: #fff;

// Create a Squircle with the `Squircle` component:
  Lorem ipsum

React HOC (higher-order component)

import { squircle } from 'corner-smoothing'

// Create a Squircle with the `squircle` HOC:
const MySquircle = squircle(StyledSquircle, {
  cornerRadius: 20,
  borderWidth: 1

Vanilla function

Zero dependencies.

import { squircleObserver } from 'auto-text-size'

// squircleObserver runs the returned function directly and
// re-runs it when the element changes size.
const renderSquircle = squircleObserver(element, options)

// There is normally no need to call this manually.

// Disconnect the resize observer when done.


import { renderSquircle } from 'corner-smoothing'


The options are the same as for the React component, excluding the as property.


Name Type Default Description
cornerRadius number Similar to the CSS property border-radius.
cornerSmoothing number 1 The degree of corner smoothing as a number in the range 0–1. 0 is equivalent to no smoothing and looks like normal border-radius. 1 indicates maximal smoothing.
preserveSmoothing boolean true Allow corner smoothing to work better on large rounded corners.
borderWidth number undefined If defined, the border mode is used.
as string | ReactComponent 'div' The underlying component that Squircle will use. Only available for the Squircle React component.

Optional props to override corner radius for individual corners.

Name Type
topLeftCornerRadius number
topRightCornerRadius number
bottomRightCornerRadius number
bottomLeftCornerRadius number


When developing one typically wants to see the output in the example application without having to publish and reinstall. This is achieved by linking the local package into the example app.

Because of issues with yarn link, Yalc is used instead. A linking approach is preferred over yarn workspaces since we want to use the package as it would appear in the real world.

npm i yalc -g
yarn watch

# Other terminal
cd example
yalc link corner-smoothing
yarn dev

Yalc and HMR

Using yalc link (or yalc add--link) makes it so that Next.js HMR detects updates instantly.


# Update version number
yarn clean && yarn build
npm publish


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