Leo - Brave's Design System

Tokens

The tokens part of this package is supposed to be used together with the Design Tokens plugin for Figma. It transforms the exported design tokens using Amazon style dictionary. Destination formats for these tokens include CSS variables, Tailwind configuration, C++ (skia variables), Java and Swift. The output files will be created at /build by running npm run transform-tokens which will also run upon install - regularly or when this package is used as a dependency.

Web Components

This package contains a set of UI components at /web-components that can be used in any browser rendering environment. They are aimed to be compatible with the majority of modern rendering engines, not only those used within Brave Browser.

Whilst they are developed using Svelte, they are intended to be used as Web Components, usable in many different frameworks or from vanilla HTML and Javascript.

The Web Components require compliation - they are not precompiled in this repo:

• Run vite / sveltekit / rollup or webpack with a svelte plugin
• Ensure that this repo's postcss plugin at postcss/theme.js is added to your configuration for svelte's preprocess. See example in .storybook/main.js and svelteOptions.

Platform specifics

CSS

To get started with the CSS variables exported, you must have the contents of build/css/variables.css included in your html page. Perhaps directly through a <link rel="stylesheet"> element, or indirectly through webpack's css-loader and import '@brave/leo/build/css/variables.css'.

Typography

Individual typography variables are available but so are convenient combined font declarations:

--typography-text-default-regular-font-size: 14px;
--typography-text-default-regular-letter-spacing: 0;
--typography-text-default-regular-line-height: 20px;
--typography-text-default-regular-paragraph-indent: 0;
--typography-text-default-regular-paragraph-spacing: 0;

--font-text-default-regular: 400 14px/20px Poppins;

Colors

Any color in Brave's standard or extended palettes is available in a dark and light versions:

--color-light-text-primary: rgb(29, 31, 37);
--color-dark-text-primary: rgb(236, 239, 242);

However, there are color variables which will select the light or dark version automatically:

/* sometimes this */
--color-text-primary: rgb(29, 31, 37);

/* or this */
--color-text-primary: rgb(236, 239, 242);

The relevant light or dark version is selected by:

• The current global @media (prefers-color-scheme: [value]) value
• The closest HTML ancestor with a data-theme attribute, e.g.

<div class="footer" data-theme="dark">
  <p style="color: var(--color-text-primary);">I am always in dark mode</p>
</div>

All Web Components and css variables aim to use the color theme according to the nearest ancestor which defines an override using a `data-theme="[dark|light]" attribute

Tailwind

A tailwind config, complete with plugin, is available at @brave/leo/build/tailwind/index.js. Once you configure this, all variables should be available using the theme() function.