Getting Started

Introduction to Master CSS

The CSS language and framework for rapidly building modern and high-performance websites.

A CSS language

Master CSS is a markup-driven CSS language with smart rules allowing you to write familiar CSS using concise syntax within HTML/JSX.

Under the hood, Master CSS automatically adds vendor prefixes, smartly ordering CSS rules, and more. This allows you to focus on building your website rather than spending a lot of effort writing and maintaining CSS rules.

Hello World

<h1 class="fg:indigo fg:red:hover font:32 font:40@sm font:heavy m:10x text:center">
    Hello World
</h1>

Declaring styles through the class attribute, attaching selector states, and even base them on applying conditionally. There's no need to write any inline style sheets, including creating external CSS files; just add syntax classes in your HTML.

You can write atomic classes text:center or abstract styles btn based on the characteristics of your project and team.

A CSS framework

Master CSS is a standalone CSS framework that provides various packages and solutions to expedite the development, including integrations for popular JavaScript frameworks, code linting for unifying team style, language service to enhance the developer experience, configuration API for design systems, and more.

View all official packages

Package	Description
Main
@master/css	The CSS language and framework for rapidly building modern and high-performance websites
@master/css-runtime	Run Master CSS right in the browser
@master/css-server	Render Master CSS on the server side
@master/css-extractor	Master CSS static extractor for various raw text
@master/css-validator	Validate Master CSS syntax
@master/css-cli	Master CSS CLI
@master/create-css	Initialize a new Master CSS project
Integrations
@master/css.react	Integrate Master CSS in React way
@master/css.svelte	Integrate Master CSS in Svelte way
@master/css.vue	Integrate Master CSS in Vue way
@master/css.nuxt	Integrate Master CSS Progressive Rendering in Nuxt way
@master/css-extractor.vite	Integrate Master CSS Static Extraction in Vite way
@master/css-extractor.webpack	Integrate Master CSS Static Extraction in Webpack way
Developer Tools
@master/eslint-config-css	Master CSS ESLint Config
@master/eslint-plugin-css	Master CSS ESLint Plugin
@master/css-language-server	Master CSS Language Server
@master/css-language-service	Master CSS Language Service
master-css-vscode	Master CSS for Visual Studio Code
Other Solutions
@master/colors	A crafted color system for beautiful user interfaces
@master/normal.css	Normalize browser's styles ~600B
theme-mode	A lightweight utility for switching CSS theme modes
class-variant	Create reusable and extensible style class variants

Why Master CSS?

The reasons why to use Master CSS with an overview of features, syntax benefits, benchmarks, and a comprehensive comparison:

Minimal CSS Output

This is a real-world benchmark of critical CSS on page load for well-known official documentation websites.

322 kB

( 21.1 kB + Font 7.1 kB + Normal 1.7 kB )

322 kB

React, 3.6x larger

322 kB

Vue.js, 4.0x larger

322 kB

Angular, 4.2x larger

322 kB

Material UI, 6.0x larger

322 kB

Next.js, 6.1x larger

322 kB

Bootstrap, 9.8x larger

322 kB

Tailwind CSS, 10.7x larger

The results are the size sum of internal CSS and external CSS, including font CSS

According to HTTP Archive CSS Bytes, the sum of transfer size kilobytes of all external stylesheets requested by the page is ~82 kB, excluding internal and inline styles.

Master CSS only injects the CSS required by the page, so the official documentation site is super tiny, about ~6 kB per page (brotli).

Master CSS provides three rendering modes, and you can choose according to project scale and application scenarios to meet your business needs.

One of the most unique, the progressive rendering works by pre-rendering the critical CSS based on the element's class names and deferring the loading of the runtime engine for any future dynamic class names.

<!DOCTYPE html>
<html lang="en">
<head>
    …
    <!-- Generate only the critical CSS required for the page. -->
    <style id="master">
       .block {
           display: block
       }
    </style>
    <script src="https://cdn.master.co/css-runtime@rc" defer></script>
</head>
<body>
    <h1 class="block">Hello World</h1>
</body>
</html>

This ensures the page generates the ultra-lightweight CSS and the fastest first-page render, unlike traditionally bundling styles across the entire application.

Initially, Master CSS was intended to create a CSS engine for production browser runtimes, so we concentrated on performance such as syntax parsing, rule generation, cache sharing, and even browser rendering.

Master CSS doesn't use heavy-duty build tools like PostCSS, Autoprefixer, or any minifiers, as these rules are generated with optimization.

Custom Design Systems

Master CSS provides rich configuration to help you build a consistent, easy-to-manage, and scalable design system. We've built a series of neutral design tokens and created a universal Master Design System, which makes your design system on top of or use it as a quick starting point.

Variable	Description
Colors	Customizing color variables or starting with the crafted palette.
Primitive Colors	Customizing primitive color variables or starting with the official design system.
Frame Colors	Customizing frame color variables or starting with the official design system.
Text Colors	Customizing text color variables or starting with the official design system.
Fonts	Customizing fonts for your design system.
Screens	Customizing screen sizes and breakpoints for your design system.
Spacing and Sizing	Apply consistent sizes across your application.

This is just one part; more design variables and tokens are scattered throughout the syntax documentation.

Innovative Syntax Highlighting

Master CSS is the first language to highlight class names fully, making identifying their properties, appearance, and state faster.

Do you find writing utility classes sometimes seem lengthy or hard to read?

<div class="sm:hover:bg-[#ceb195] …">

Light up your class names in markup from now on!

<div class="bg:
#ceb195:hover@sm …">

This feature is included in the Master CSS Language Service.

Reliable Code Linting

Have you ever felt anxious about adding styles to class attributes? Master CSS was the first to introduce syntax validation of classes in template markup, which helps you find errors early before building and dramatically improves the developer experience.

Invalid value for `font` property.

<div class="font:">…</div>

This is just a piece of cake; we also allow you to enforce consistent class ordering, legitimate class checks, class collision checks, and checks for JavaScript utilities like clsx().

To learn more, check out the Code Linting documentation.

Comparisons

Here’s a comprehensive comparison of Master CSS, Tailwind CSS and Bootstrap:


	Master CSS	Tailwind CSS	Bootstrap
Language		-	-
Framework
Rendering
Runtime Rendering		Dev JIT
Server-side Rendering
CSS Hydration
Static Extraction
Preprocessors
PostCSS	No	Yes	Yes
Autoprefixer	No	Yes	Yes
CSS minifiers	No	Yes	Yes
Resource Size
Critical CSS for initial paint	Minimal	Largest	~233 KB
Source that generates CSS	Page	All files	-
Generate redundant CSS rules	No	Yes	Yes
Render-blocking CSS resources	Internal	External	External
Programming
The class names from server			-
The class names from static files		Unreliable	-
The ability to customize tokens
Breakpoints and Screens	11	5	5
Colors	~222	~244	~100
Variables with Modes
Selectors
Abstract Styles		`@apply`	Predefined
Language Service
Code-completion
Syntax highlighting for class names
CSS generate preview
Code Linting for Markup
Consistent class order
Syntax error checks
Disallow unknown classes
Class collision detection

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