roxcss

roxcss is a runtime atomic CSS engine. It is a template-string tag function that parses class names on the fly and injects the matching CSS rules into the document. No build step, no configuration file, no purge phase — whatever class name you write, the rule is generated when it is first used.

roxcss 是一个运行时原子 CSS 引擎。它是一个模板字符串标签函数，在调用时动态解析类名并注入对应的 CSS 规则。没有构建步骤、没有配置文件、没有清除阶段——你写出什么类名，规则就在首次使用时生成。

Features / 特性

Zero build, zero config — rules are generated and injected at runtime, the first time a class name is used. Nothing to precompile.
Framework-agnostic — works anywhere a template-string tag works: plain HTML, Vue, React, and more.
No hidden class names — the class you write is the class in the DOM and the selector in DevTools. What you see is what you typed.
Values, not magic — w-170px means exactly width: 170px. No numeric scale sits between the class name and the CSS.
Tailwind-style preset — a built-in preset reuses Tailwind v4 utility names, ready to extend or replace (see Default Preset / 默认预设).
Synchronous — the rules are live the moment the call returns.
零构建、零配置：类名首次使用时，规则在运行时生成并注入，无需任何预编译。
框架无关：任何模板字符串标签可用的地方都能用——原生 HTML、Vue、React 等。
类名即真相：你写下的类名就是 DOM 中的类、DevTools 中的选择器。所见即所写。
无魔法值：w-170px 就是 width: 170px。类名与 CSS 之间没有数值刻度。
Tailwind 风格预设：内置预设复用 Tailwind v4 工具类命名，可自由扩展或替换（见 Default Preset / 默认预设）。
天生同步：调用返回的瞬间，规则已经生效。

Quick Start / 快速开始

Install the package, then import the default instance and use it as a template tag. The class names you write are returned unchanged, and the matching rules are injected into <head>:

安装依赖后导入默认实例 rox，并把它作为模板标签使用。你写下的类名会原样返回，匹配的规则注入 <head>：

npm install roxcss

import { rox } from "roxcss";

// class names are returned unchanged / 类名原样返回
const className = rox`flex flex-col gap-16px p-24px rounded-8px hover:bg-blue`;

document.body.className = className;
// <body class="flex flex-col gap-16px p-24px rounded-8px hover:bg-blue">

The call injects these rules into a <style data-roxcss> element in <head>:

这次调用向 <head> 中的 <style data-roxcss> 元素注入以下规则：

[class~="flex"] {
  display: flex;
}
[class~="flex-col"] {
  display: flex;
  flex-direction: column;
}
[class~="hover:bg-blue"]:hover {
  background: blue;
}

The tag function is sync: when the call returns, the rules are live. Repeated calls with the same class names hit the cache and never touch the style layer again — steady-state rendering costs nothing beyond the returned string.

标签函数是同步的：调用返回时规则已生效。相同类名的重复调用命中缓存，之后不再触碰样式层——稳定态渲染除了返回字符串外零开销。

rox is the out-of-the-box instance built on the default preset. When you need a preset-free setup — a design system with its own vocabulary, a framework-specific shim, or an experiment — build your own matcher tree with createRox. The minimal instance below registers two spacing utilities and one layout utility, plus an md breakpoint modifier:

rox 是基于默认预设的开箱即用实例。当需要脱离预设——自有词汇的设计系统、框架专用垫片或临时实验——用 createRox 自建 matcher 树。下面的最小实例注册了两个间距工具、一个布局工具，以及 md 断点修饰符：

import { createRox } from "roxcss";

const myRox = createRox({
  matchers: {
    p: (v) => `padding:${v}`,
    m: (v) => `margin:${v}`,
    flex: {
      "": () => "display:flex",
      col: () => "display:flex;flex-direction:column",
    },
  },
  modifiers: {
    md: (selector, cssDecl) => `@media (min-width: 768px) { ${selector} { ${cssDecl} } }`,
  },
});

myRox`md:flex-col p-16px`;
// the media-wrapped rule is injected / 媒体查询包裹的规则被注入

CDN Usage / CDN 用法

No install, no bundler — load the package straight from a CDN in a plain HTML page. Two builds are published; pick one by how you use roxcss:

无需安装、无需打包——在普通 HTML 页面中直接从 CDN 加载。两个构建按使用方式选择：

Full build / 全量构建

The default build bundles the default preset — rox, createConfig, createModifiers, and the breakpoint table — ready to use:

默认构建内置默认预设——rox、createConfig、createModifiers 与断点表——开箱即用：

<script type="module">
  import { rox } from "https://unpkg.com/roxcss/index.min";

  // class names are returned unchanged, rules are injected / 类名原样返回并注入规则
  document.body.className = rox`flex flex-col gap-16px p-24px hover:bg-blue`;
</script>

Core build / 核心构建

The core build ships only the engine — createRox plus the DOM injection — at about 2 kB minified. Use it when you bring your own matchers and skip the preset:

核心构建只含引擎——createRox 与 DOM 注入——压缩后约 2 kB。自带 matcher、不需要预设时使用：

<script type="module">
  import { createRox } from "https://unpkg.com/roxcss/core.min";

  // build your own matchers, no default preset / 自建 matcher，无默认预设
  const rox = createRox({
    matchers: {
      p: (v) => `padding:${v}`,
      bg: (v) => `background:${v}`,
    },
  });
  document.body.className = rox`p-24px bg-blue`;
</script>

Both URLs serve the latest published version from unpkg; pin an exact version in production, e.g. https://unpkg.com/roxcss@0.0.0/index.min.

两个 URL 均由 unpkg 提供最新发布版本；生产环境建议固定版本，如 https://unpkg.com/roxcss@0.0.0/index.min。

How It Works / 工作方式

A token is split by - into segments, and the segments walk a nested matcher tree with two kinds of nodes — functions and objects:

token 按 - 拆成段，段在嵌套的 matcher 树中逐段查找。节点只有两种——函数与对象：

Function node / 函数节点

A function swallows the remaining segments and is called with one argument per segment. It returns the declaration text — or null to mark failure.

函数吞掉剩余所有段，剩余段每段一个参数调用，返回声明文本——返回 null 表示失败。

// matcher definition (a function node) / matcher 定义（函数节点）
p: (v) => `padding:${v}`;

// token flow / token 解析流程
//   p-24px
//     → segments ["p", "24px"]
//     → "p" is a function, swallows the rest → p("24px")
//     → padding:24px

Object node / 对象节点

An object is a container that remaining segments descend through as keys. The "" key is the fallback — used when the segments run out or no key matches.

对象是容器，剩余段作为键逐层下行。"" 键是兜底——段耗尽或无键匹配时使用。

// matcher definition (an object node) / matcher 定义（对象节点）
flex: {
  "": () => "display:flex",
  col: () => "display:flex;flex-direction:column",
}

// token flow / token 解析流程
//   flex-col
//     → segments ["flex", "col"]
//     → "flex" is an object, descend by key "col" → flex.col()
//     → display:flex;flex-direction:column
//   flex
//     → segments ["flex"], segments run out, object has "" → flex[""]()
//     → display:flex

Match resolution, in order: exact key → "" fallback → failure. On failure the token is returned unchanged and no rule is injected. A function returning null also means failure.

匹配解析顺序：精确键 → "" 兜底 → 失败。失败时 token 原样返回且不注入规则。函数返回 null 同样视为失败。

Prefixes: pseudo-classes and environment modifiers / 前缀：伪类与环境修饰符

Tokens split by : — the first parts are prefixes, the last part is the matcher key. Each prefix part is checked against the modifiers registry: registered ones are environment modifiers (at most one — they wrap the whole rule in @media, .dark, etc.), the rest are treated as pseudo-classes and appended to the selector freely in any order and amount.

token 按 : 拆分——前面的部分是前缀，最后一段是 matcher 键。每个前缀段先查 modifiers 注册表：命中的是环境修饰符（最多一个——它把整条规则包裹进 @media、.dark 等环境），其余一律视为伪类，任意数量、任意顺序拼接到选择器上。

// → [class~="hover:p-8px"]:hover { padding:8px }
myRox`hover:p-8px`;

// → @media (min-width:768px) { [class~="md:flex-col"] { display:flex;flex-direction:column } }
myRox`md:flex-col`;

// → @media (min-width:768px) { [class~="md:hover:focus:p-8px"]:hover:focus { padding:8px } }
myRox`md:hover:focus:p-8px`;

Cache / 缓存

Each token is resolved exactly once per instance. Injected and failed tokens are remembered in two Sets — a repeated render costs a single cache lookup and nothing else.

每个 token 在每个实例中只解析一次。已注入与已失败的 token 分别记入两个 Set——重复渲染只付出一次缓存查询，再无其他。

API / API 参考

`createRox(options)`

createRox creates a fully independent instance with its own matcher tree, injection caches (injected / failed), and rule memory. Multiple instances can coexist without sharing any state. Pair it with createConfig for a preset-based instance, or pass a hand-written tree for a preset-free one:

createRox 创建完全独立的实例——各自的 matcher 树、注入缓存（injected / failed）与规则内存。多个实例可并存，互不共享状态。配合 createConfig 得到基于预设的实例；传入手写 matcher 树则脱离预设：

matchers Record<string, MatcherNode>
- the matcher tree. Keys are segment roots, values are functions or nested objects (see How It Works / 工作方式).
- matcher 树。键是段根，值是函数或嵌套对象（见 How It Works / 工作方式）。
modifiers Record<string, Modifier> (optional / 可选)
- environment modifier registry, keyed by prefix name. Defaults to an empty registry, in which case every prefix is treated as a pseudo-class.
- 环境修饰符注册表，以前缀名为键。默认空注册表，此时所有前缀都按伪类处理。

`RoxInstance`

The object returned by createRox — a callable template tag carrying a getCSS method.

createRox 的返回值——可调用的模板标签函数，挂载 getCSS 方法。

interface RoxInstance {
  (strings: TemplateStringsArray, ...values: unknown[]): string;
  getCSS(): string;
}

(strings, ...values)
- tag invocation: splits the interpolated string on whitespace, resolves each token, and joins the results with a space — the class-name string you can put on an element. Rules are flushed synchronously when the call returns.
- 标签调用：按空白拆分插值后的字符串，逐个解析 token，用空格连接结果——即可直接放到元素上的类名字符串。调用返回时规则同步写入。
getCSS()
- returns every rule the instance has injected so far, joined with newlines. Useful for SSR style collection and debugging; works even without a DOM.
- 返回实例迄今注入的全部规则，换行连接。适用于 SSR 样式收集与调试，无 DOM 时同样可用。

`rox`

The default instance: createRox(createConfig()) — the out-of-the-box matcher tree plus sm–2xl breakpoint modifiers. Use it directly when the default preset fits; build a custom instance with the factories below when it does not.

默认实例：createRox(createConfig())——开箱即用的 matcher 树加 sm–2xl 断点修饰符。默认预设适用时直接使用；不适用时用下面的工厂函数构建自定义实例。

`createConfig(overrides?)`

Creates the default preset — a fresh matcher tree (90+ top-level roots) plus fresh breakpoint modifiers. Every call rebuilds the whole tree, so instances sharing a config never share references.

创建默认预设——全新的 matcher 树（90+ 顶层根）与全新的断点 modifiers。每次调用整树重建，共享同一 config 的实例之间零引用共享。

overrides PresetOverrides (optional / 可选)
- recursive overrides merged on top of the defaults (see Customization / 自定义).
- 递归覆盖参数，合并到默认配置之上（见 Customization / 自定义）。

`createModifiers(breakpoints?)`

Creates breakpoint environment modifiers from a name → pixel table. The passed table completely determines the output — no implicit merging with the default.

根据"名称 → 像素"表创建断点环境修饰符。传入的表完全决定输出——不会隐式合并默认断点。

createModifiers({ ...defaultBreakpoints, xxl: 1700 });
// each breakpoint name produces a min-width media query / 每个断点名生成一条 min-width 媒体查询

`defaultBreakpoints`

Breakpoint / 断点	Min-width / 最小宽度
`sm`	640px
`md`	768px
`lg`	1024px
`xl`	1280px
`2xl`	1536px

Types / 类型

Every type is exported from roxcss alongside the functions. The structural types are spelled out in the entries above; the core shapes are:

全部类型与函数一同从 roxcss 导出。结构性类型的完整定义见上方 API 条目，核心形状如下：

MatcherFunction (...args: string[]) => string | null
- leaf of the matcher tree; one argument per remaining segment. Returning null marks failure.
- matcher 树叶子；剩余段每段一个参数。返回 null 表示匹配失败。
MatcherNode MatcherFunction | { [key: string]: MatcherNode }
- a leaf function, or a nested container whose keys are segment names and whose "" key is the fallback.
- 叶子函数，或嵌套容器——键是段名，"" 键为兜底。
Modifier (selector: string, cssDecl: string) => string
- wraps a complete rule in an environment (@media, .dark, …) given the final selector and declaration.
- 根据最终选择器与声明，把完整规则包裹进环境（@media、.dark 等）。
MatcherPatch MatcherFunction | null | { [key: string]: MatcherPatch }
- the override shape for createConfig: same as MatcherNode, plus null to delete a key.
- createConfig 的覆盖形状：与 MatcherNode 相同，多出的 null 表示删除键。
RoxOptions { matchers: Record<string, MatcherNode>; modifiers?: Record<string, Modifier> }
- the input of createRox.
- createRox 的入参。
Preset { matchers: Record<string, MatcherNode>; modifiers?: Record<string, Modifier> }
- the output of createConfig.
- createConfig 的返回。
PresetOverrides { matchers?: Record<string, MatcherPatch>; modifiers?: Record<string, Modifier | null> }
- the input of createConfig.
- createConfig 的覆盖入参。
RoxInstance — see the RoxInstance entry above: a callable template tag with getCSS.
- 见上方 RoxInstance 条目：可调用模板标签 + getCSS。

Customization / 自定义

Writing matchers / 编写 matcher

Recall the matcher shape from How It Works / 工作方式: each remaining segment arrives as one argument, and the function returns the declaration string. In practice, single-segment values read the argument directly, while multi-segment values spread:

回顾 How It Works / 工作方式中的 matcher 形态：剩余段每段一个参数，函数返回声明字符串。实际写法上，单段值直接读取参数，多段值用 rest 展开：

createRox({
  matchers: {
    // one segment / 单段：text-14px → font-size:14px
    text: (v) => `font-size:${v}`,
    // multiple segments joined with spaces / 多段空格连接：rounded-4px-8px → border-radius:4px 8px
    rounded: (...vs) => `border-radius:${vs.join(" ")}`,
  },
});

A function returning null marks the token as failed (warning in dev, nothing injected).

函数返回 null 表示匹配失败（开发环境警告，不注入）。

Writing modifiers / 编写 modifier

A modifier receives the final selector and the CSS declaration, and returns a full rule:

modifier 接收最终选择器与 CSS 声明，返回完整规则：

const modifiers = {
  dark: (selector, cssDecl) => `.dark ${selector} { ${cssDecl} }`,
  maxLg: (selector, cssDecl) => `@media (max-width: 1024px) { ${selector} { ${cssDecl} } }`,
};

Extending the default preset / 扩展默认预设

createConfig accepts recursive overrides: objects merge key by key (defaults survive), functions and other values replace wholesale, null deletes a key. The engine treats any non-function non-object value as "key absent", so deletion needs no special case.

createConfig 支持递归覆盖：对象逐键合并（默认键保留），函数与其他值整体替换，null 删除键。引擎把非函数非普通对象的值一律视为"键不存在"，删除因此无需特判。

import { createRox, createConfig } from "roxcss";

const rox = createRox(
  createConfig({
    modifiers: {
      lg: (selector, cssDecl) =>
        // override / 覆盖默认的 min-width 语义
        `@media (max-width: 1024px) { ${selector} { ${cssDecl} } }`,
    },
    matchers: {
      // merge into the default flex subtree / 合并进默认 flex 子树
      flex: { half: () => "flex:1 1 calc(50% - 8px)" },
      // replace a whole subtree / 整体替换某子树
      shadow: () => "box-shadow:var(--shadow)",
      // delete a root / 删除某个根
      animate: null,
    },
  }),
);

Working with CSS variables / 配合 CSS 变量

roxcss does not interpret values, so CSS variables compose naturally. A common pattern is a private helper that turns segments into a var() reference:

roxcss 不解析值，CSS 变量因此天然可组合。常见做法是私有 helper 把段拼成 var() 引用：

// segments → var(--accent-bg) / 段 → var(--accent-bg)
const cssVar = (vs: string[]) => `var(--${vs.join("-")})`;

createRox(
  createConfig({
    matchers: {
      color: (...vs) => `color:${cssVar(vs)}`,
      bg: (...vs) => `background:${cssVar(vs)}`,
      border: {
        color: (...vs) => `border-color:${cssVar(vs)}`,
        t: () => "border-top:1px solid var(--border)",
      },
    },
  }),
);

Default Preset / 默认预设

The default preset borrows its vocabulary from Tailwind v4 — the same utility names, the same nesting — so familiar classes keep their meaning. Two conventions differ from Tailwind, and knowing them once is enough to read everything below:

默认预设的词汇取自 Tailwind v4——相同的工具类名、相同的嵌套结构——熟悉的类名含义不变。两处约定与 Tailwind 不同，先了解它们，下面的示例就都能读懂：

Values carry their units / 值自带单位

roxcss has no numeric scale: p-4 does not mean 1rem as it does in Tailwind. Write the full value and it lands in the declaration verbatim — p-4px → padding:4px, w-170px → width:170px. A bare number produces invalid CSS; that is a caller error.

roxcss 没有数值刻度：p-4 不像在 Tailwind 中那样表示 1rem。单位写全，值原样进入声明——p-4px → padding:4px、w-170px → width:170px。裸数字会生成无效 CSS，属调用方错误。

`text` is size, `color` is color / `text` 管字号，`color` 管颜色

Tailwind overloads text-* for both sizing and coloring; roxcss keeps them apart — text-16px sets font-size, color-red sets color.

Tailwind 用 text-* 兼任字号与颜色；roxcss 分开处理——text-16px 设置字号，color-red 设置颜色。

Utilities by category / 按类别示例

The preset covers layout, spacing, typography, borders, colors, and effects. A selection follows, grouped by category; the full listing lives in docs/预设设计.md.

预设覆盖布局、间距、排版、边框、颜色与效果。以下按类别节选，完整清单见 docs/预设设计.md。

Layout / 布局

flex              → display:flex
flex-col          → display:flex;flex-direction:column
grid-cols-3       → display:grid;grid-template-columns:repeat(3,minmax(0,1fr))
items-center      → align-items:center
justify-between   → justify-content:space-between
gap-16px          → gap:16px
p-24px            → padding:24px
w-170px           → width:170px

Typography / 排版

text-16px         → font-size:16px
text-center       → text-align:center
font-bold         → font-weight:700
leading-16px      → line-height:16px
underline         → text-decoration-line:underline
truncate          → overflow:hidden;text-overflow:ellipsis;white-space:nowrap

Borders, colors & effects / 边框、颜色与效果

rounded-5px       → border-radius:5px
border-2px-solid-red → border:2px solid red
bg-blue           → background:blue
color-red         → color:red
duration-150ms    → transition-duration:150ms
delay-75ms        → transition-delay:75ms

Position, overflow & more / 定位、溢出与其他

relative          → position:relative
inset-x-0         → inset-inline:0
z-10              → z-index:10
overflow-x-auto   → overflow-x:auto
hidden            → display:none
list-none         → list-style:none
aspect-16/9       → aspect-ratio:16/9

Families share a pattern: every side and axis variant exists — m mirrors p, overflow-y mirrors overflow-x, and so on.

工具类家族遵循同一模式：每个方向与轴向的变体都存在——m 与 p 对应，overflow-y 与 overflow-x 对应，依此类推。

Breakpoints come from createModifiers() with defaultBreakpoints, all min-width media queries. Prefix a class name with a breakpoint and it applies from that width up:

断点由 createModifiers() 基于 defaultBreakpoints 生成，全部为 min-width 媒体查询。在类名前加断点前缀，规则从该宽度起生效：

<div class="flex-col lg:flex-row">…</div>

Framework Usage / 框架用法

Because class names are returned as plain strings, any class binding works. The string can be produced anywhere — a computed property, an inline handler, or a plain function — and handed to a framework's binding. A Vue example:

类名以普通字符串返回，因此任何 class 绑定方式都适用。字符串可以在任何位置生成——computed、事件处理器或普通函数——再交给框架的绑定。Vue 示例：

<script setup lang="ts">
import { rox } from "./rox"; // your configured instance / 你配置好的实例
</script>

<template>
  <button
    type="button"
    :class="
      rox`inline-flex font-mono text-16px px-10px rounded-5px
           hover:bg-blue focus-visible:bg-blue`
    "
  >
    Click me
  </button>
</template>

Performance & Injection / 性能与注入

Batch flush per call. All new rules from one call are appended to the active <style> bucket in a single textContent write — one parse, one style invalidation. No per-rule insertRule (measured O(N²) under interleaved forced layout; see 性能分析.md).
Rolling style buckets. The active <style data-roxcss> element is reused until it holds 1000 rules, then frozen and a new one is created. Bucket count stays at ceil(rules / 1000) — no DevTools panel clutter.
SSR safe. With no DOM, rules are kept in memory and readable via getCSS().
每次调用批量写入：一次调用产生的新规则，以一次 textContent 赋值追加到活动 <style> 桶——一次解析、一次样式失效。不使用逐条 insertRule（实测在交替强制布局场景退化为 O(N²)，见性能分析.md）。
滚动 style 桶：活动 <style data-roxcss> 元素复用到 1000 条规则后冻结，新建下一个。桶数保持在 ceil(规则数 / 1000)——DevTools 面板不堆积。
SSR 安全：无 DOM 时规则保存在内存，经 getCSS() 读取。

Docs / 设计文档

The design docs are written in Chinese and archived under docs/:

设计文档以中文撰写，归档在 docs/：

Doc / 文档	Content / 内容
设计方案.md	Engine architecture, token parsing, matcher lookup.
	引擎架构、token 解析、matcher 查找。
预设设计.md	Default preset design and full utility listing.
	默认预设设计与完整工具类清单。
样式表管理策略.md	Rolling `<style>` bucket injection design.
	style 滚动桶注入设计。
性能分析.md	Performance model and measurements.
	性能模型与实测。
tailwind对齐计划.md	Tailwind v4 alignment decisions and gaps.
	Tailwind v4 对齐决策与差距。

Name		Name	Last commit message	Last commit date
.github/workflows		.github/workflows
.vite-hooks		.vite-hooks
.vscode		.vscode
docs		docs
packages/example		packages/example
src		src
tests		tests
.gitignore		.gitignore
AGENTS.md		AGENTS.md
README.md		README.md
package.json		package.json
pnpm-lock.yaml		pnpm-lock.yaml
pnpm-workspace.yaml		pnpm-workspace.yaml
tsconfig.json		tsconfig.json
vite.config.ts		vite.config.ts

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roxcss

Features / 特性

Quick Start / 快速开始

CDN Usage / CDN 用法

Full build / 全量构建

Core build / 核心构建

How It Works / 工作方式

Function node / 函数节点

Object node / 对象节点

Prefixes: pseudo-classes and environment modifiers / 前缀：伪类与环境修饰符

Cache / 缓存

API / API 参考

createRox(options)

RoxInstance

rox

createConfig(overrides?)

createModifiers(breakpoints?)

defaultBreakpoints

Types / 类型

Customization / 自定义

Writing matchers / 编写 matcher

Writing modifiers / 编写 modifier

Extending the default preset / 扩展默认预设

Working with CSS variables / 配合 CSS 变量

Default Preset / 默认预设

Values carry their units / 值自带单位

text is size, color is color / text 管字号，color 管颜色

Utilities by category / 按类别示例

Layout / 布局

Typography / 排版

Borders, colors & effects / 边框、颜色与效果

Position, overflow & more / 定位、溢出与其他

Framework Usage / 框架用法

Performance & Injection / 性能与注入

Docs / 设计文档

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