css-extras

A collection of useful CSS custom functions

A comprehensive collection of CSS custom functions that leverage the new native CSS @function rule.

No build step required! Feel free to copy-paste what you need. No credit needed.

[!CAUTION] Work in progress.

Requirements

Currently only supported in Chrome 141+. The @function rule is going through the W3C standardization process and will be available in other browsers soon.

Install

npm install css-extras

Usage

@import 'css-extras';

Or link directly in HTML:

<link rel="stylesheet" href="node_modules/css-extras/index.css">

Then use any of the functions in your CSS:

.element {
	/* Math functions */
	padding: --negate(var(--spacing));
	width: --lerp(100px, 200px, 0.5);

	/* Color functions */
	background: --opacity(blue, 50%);
	border-color: --tint(var(--primary-color), 20%);

	/* Typography */
	font-size: --fluid-type(16px, 24px);

	/* Layout */
	border-radius: --conditional-radius(1rem);

	/* And many more! */
}

Demo (requires Chrome 141+)

Functions

This package includes ~43 CSS custom functions organized into these categories:

• Math & Number - Mathematical operations and calculations
• Color - Color manipulation, generation, and accessibility helpers
• Typography - Fluid type scaling and line height
• Layout - Responsive layouts and aspect ratios
• Spacing - Consistent spacing systems
• Animation - Easing functions
• Grid - Responsive grid helpers
• Filter - Shadows and effects
• Theme - Light/dark mode utilities
• Utility - Unit conversion and helpers

Complete function reference

Examples

Responsive card component

.card {
	/* Conditional border radius */
	border-radius: --conditional-radius(1rem);

	/* Smooth shadow */
	box-shadow: --smooth-shadow(rgb(0 0 0 / 0.2), 16px, 3);

	/* Fluid spacing */
	padding: --spacing(4);
	margin-block: --spacing(3);

	/* Theme-aware background */
	background: --theme-color(var(--card-bg), 95%, 10%);

	/* Fluid typography */
	font-size: --fluid-type(14px, 16px, 320px, 1280px);
}

.card-title {
	font-size: --modular-scale(1rem, 1.25, 2);
	color: --shade(var(--primary-color), 20%);
}

.card:hover {
	transform: translateY(--negate(4px));
	box-shadow: --glow(var(--primary-color), 20px, 0.3);
}

Responsive layout

.layout {
	display: grid;
	grid-template-columns: --sidebar-layout(280px, 50ch);
	gap: --spacing(4);
	padding: --container-padding(2rem, 1400px);
}

.content-grid {
	display: grid;
	grid-template-columns: --auto-grid(300px, 3);
	gap: --spacing(3);
}

.responsive-element {
	padding: --responsive-value(1rem, 2.5rem, 320px, 1200px);
	font-size: --responsive-value(14px, 18px, 320px, 1200px);
}

Theme-aware components

IMPORTANT: Theme functions require color-scheme: light dark to work:

:root {
	color-scheme: light dark; /* Required! */
}

.button {
	/* Theme-aware values (works with ANY value type!) */
	color: --light-dark(black, white);
	background: --theme-color(var(--brand-color), 90%, 20%);
	border-color: --light-dark(#d1d5db, #374151);

	/* Works with non-color values too */
	padding: --light-dark(0.5rem 1rem, 0.75rem 1.5rem);
	font-weight: --light-dark(500, 400);
	background-image: --light-dark(url(icon-light.svg), url(icon-dark.svg));
}

Browser support

Check caniuse.com.

Related

• sass-extras - Useful utilities for working with Sass
• modern-normalize - Normalize browsers' default style

License

• MIT
• CC0-1.0

SPDX-License-Identifier: (MIT OR CC0-1.0)