Markdown Content Pages — Next.js

This skill defines how to build content-driven pages (blog posts, changelogs, legal pages, knowledge bases) in a Next.js App Router project using MDX.

The goal is visual and behavioral consistency between:

• Markdown codeblocks written in .mdx files (processed at build time)
• Custom React code components rendered on the page (highlighted at runtime)

Stack Overview

npm install fumadocs-mdx fumadocs-core shiki rehype-pretty-code zod

Project Structure

├── app/
│   ├── layout.tsx                       # Root layout
│   ├── styles/
│   │   ├── globals.css                  # Tailwind + stylesheet imports (order matters)
│   │   ├── prose.css                    # Self-contained typography for .prose class
│   │   ├── shiki.css                    # Code block styling (themes, line numbers, highlights)
│   │   └── theming.css                  # Color variables (light/dark) — imported first
│   └── (content)/                       # Route group for content pages
│       ├── layout.tsx                   # Content layout wrapper
│       └── [[...slug]]/
│           └── page.tsx                 # Catch-all page rendering MDX content
├── content/
│   ├── meta.json                        # Top-level page ordering
│   ├── index.mdx                        # Landing page
│   └── <category>/                      # e.g. blog/, legal/, changelog/
│       ├── meta.json                    # Category page ordering
│       └── <page>.mdx                   # Individual content pages
├── components/                          # Code block components (see Code Block Components)
├── lib/
│   ├── source.ts                        # fumadocs-core source loader
│   ├── shiki.ts                         # Shared shiki config, transformers, highlightCode()
│   └── cn.ts                            # clsx + tailwind-merge utility
├── mdx-components.tsx                   # MDX element → React component mappings
└── source.config.ts                     # fumadocs-mdx collection + rehype pipeline

Content Collection

source.config.ts

Defines two things:

1. The content collection — defineDocs() pointing at the content/ directory with a Zod-extended frontmatter schema.
2. The MDX pipeline — defineConfig() with rehype-pretty-code replacing the default fumadocs highlighter.

Key patterns:

• Call plugins.shift() inside rehypePlugins to remove the built-in fumadocs syntax highlighter, then plugins.push() rehype-pretty-code.
• Configure dual shiki themes (one light, one dark) so both color sets are embedded in the markup. CSS toggles which is visible.
• Pass custom shiki transformers that inject metadata into the AST (raw source text) for components to read at render time.
• Use onVisitTitle to add not-prose to code block title elements so prose typography doesn’t affect them.

next.config.ts

Wrap the Next.js config with createMDX() from fumadocs-mdx/next.

lib/source.ts

Create a loader() from fumadocs-core/source with a baseUrl and the collection’s .toFumadocsSource(). Export the source and a Page type via InferPageType.

Content Files

MDX Frontmatter

Every .mdx file starts with YAML frontmatter validated by the Zod schema in source.config.ts. Imports go after the closing ---. React components can be used inline alongside standard markdown. Code blocks use fenced syntax with language tags, and a title="filename.tsx" meta string adds a title bar.

meta.json

Controls page ordering within a directory — an array of slug strings:

{
  "pages": ["index", "terms-of-service", "privacy-policy"]
}

Catch-All Content Page

The [[...slug]]/page.tsx route resolves slugs via source.getPage(params.slug), returns notFound() if missing, and renders:

<article className="prose">
  <h1>{page.data.title}</h1>
  <p className="text-muted-foreground">{page.data.description}</p>
  <MDX components={getMDXComponents()} />
</article>

Export generateStaticParams using source.generateParams() for static generation.

Shiki Configuration

lib/shiki.ts

Centralizes all syntax highlighting config. Used by both the MDX pipeline (build-time) and custom code components (runtime).

This module should export:

1. A language map — Record<string, BuiltinLanguage> mapping file extensions (ts, tsx, sh, etc.) to shiki language identifiers. Plus a getLanguageFromExtension() helper.

2. Shiki transformers — run during MDX compilation, attaching custom properties to AST nodes that components read at render time. Attach the raw source string (for copy button) so the component mapping can use it.

3. highlightCode(code, language) — an async function using codeToHtml() with the same dual themes as the MDX pipeline. This is the consistency mechanism — both build-time and runtime highlighting use identical shiki config and produce the same data attributes (data-line-numbers, data-line), ensuring matching visual output everywhere.

MDX Component Mappings

mdx-components.tsx

Maps HTML elements from the MDX compiler to React components. This is the bridge between raw markdown and the component system.

Key mappings:

• code — Renders a styled inline <code> element.

• pre — Reads transformer metadata from props. Renders a <pre> with a CopyButton overlay using the raw source text.

• img — Optionally wrap with Next.js Image for optimization.

The flow: author writes fenced code block → rehype-pretty-code + shiki produce <pre><code> with syntax tokens → shiki transformers attach metadata → MDX calls these mappings → components read metadata and render accordingly.

Code Block Components

Build these client components for the code display system:

CodeBlock

Single code display. Accepts highlightedCode (HTML string), language, optional title, rawCode (for copy), maxHeight, wrap. Renders a <figure data-rehype-pretty-code-figure> with optional <figcaption> title bar, the highlighted HTML via dangerouslySetInnerHTML, and a CopyButton.

CodeBlockTabs

Multi-file tabbed code. Accepts an array of { filename, highlightedCode, rawCode } tabs. Uses controlled tab state. Renders tabs in a <figcaption> with a CopyButton for the active tab.

CopyButton

Clipboard button with visual feedback. Uses a useCopyToClipboard hook that calls navigator.clipboard.writeText() and shows a checkmark for ~2 seconds. Positioned absolutely (top-right) with opacity transition on group hover.

Styling Architecture

globals.css — Import Order

@import 'tailwindcss';
@import './theming.css';
@import './prose.css';
@import './shiki.css';

theming.css must come first — it defines the color variables that prose and shiki consume.

theming.css — Color Variables

Define light and dark mode variables consumed by shiki.css and component classes:

• --color-code — code block background
• --color-code-foreground — code block text
• --color-code-highlight — highlighted line background

prose.css — Self-Contained Typography

A hand-rolled .prose class that doesn’t depend on @tailwindcss/typography or any UI framework. Use :where() selectors to keep specificity at zero. Use .not-prose as an escape hatch for embedded components.

Cover at minimum: body color and line-height, headings (h1–h6), paragraphs, links, strong, lists (ul/ol/li), blockquotes, horizontal rules, tables, and code figures (figure[data-rehype-pretty-code-figure]).

Design decisions:

• Body text at reduced opacity (e.g. 70% of --foreground via color-mix) for softer reading
• Headings at full --foreground with tighter line-height
• Code figures with vertical margin and first/last child resets

shiki.css — Code Block Styles

Style all code blocks uniformly — MDX-rendered and component-rendered both use the same data attributes.

Key rules:

• Dual-theme switching — In .dark, swap color to var(--shiki-dark) on [data-rehype-pretty-code-figure] span. Light theme is the default; shiki embeds both color sets as CSS variables.
• Container — [data-rehype-pretty-code-figure] gets background from --color-code, rounded corners, overflow hidden.
• Line numbers — CSS counters on [data-line-numbers] [data-line]::before. Sticky left position so they stay visible on horizontal scroll.
• Line highlighting — [data-highlighted-line] gets a subtle background and left border.
• Title bar — [data-rehype-pretty-code-title] styled with mono font, muted color, bottom border.
• Text wrapping — [data-wrap='true'] code enables white-space: pre-wrap.

Consistency Model

The system ensures a fenced markdown code block and a <CodeBlock> React component produce identical visual output. This is achieved through:

1. Same shiki themes — Both MDX pipeline and highlightCode() use the same dual-theme pair.
2. Same CSS targets — Both produce [data-rehype-pretty-code-figure] elements styled by shiki.css.
3. Same data attributes — data-line, data-line-numbers, data-highlighted-line, data-wrap are used by both paths.
4. Same color variables — --color-code family from theming.css applies uniformly.
5. Shared copy button — Every code display uses the same CopyButton component.

Implementation Checklist

1. Install dependencies: fumadocs-mdx, fumadocs-core, shiki, rehype-pretty-code, zod
2. Create source.config.ts with frontmatter schema and rehype-pretty-code pipeline
3. Wrap next.config.ts with createMDX()
4. Create lib/source.ts with the source loader
5. Create lib/shiki.ts with language map, transformers, and highlightCode()
6. Create mdx-components.tsx mapping pre and code to custom components
7. Create code block components (CodeBlock, CodeBlockTabs, CopyButton)
8. Set up prose.css (self-contained typography) and shiki.css (code block styling)
9. Define theme variables in theming.css including --color-code family
10. Create content directory with meta.json files
11. Create catch-all [[...slug]]/page.tsx route
12. Import stylesheets in globals.css in correct order (theming → prose → shiki)