Customizing and Overriding Starlight Components

What You Are Learning

This tutorial explains how to customize an Astro Starlight site at three levels:

• Configuration customization: change built-in Starlight options such as title, logo, social links, table of contents, and edit links.
• CSS customization: change colors, spacing, typography, and visual details with custom CSS.
• Component overrides: replace or extend Starlight’s internal UI components when configuration and CSS are not enough.

The goal is to customize safely. Start with the least invasive option, then move to component overrides only when you need deeper control.

The Big Idea

Starlight gives you a polished documentation interface by default. You can change a lot without replacing major parts of the system.

Small visual change?
  Use custom CSS.

Built-in feature setting?
  Use astro.config.mjs.

Need to replace part of the Starlight UI?
  Use a component override.

Think of it like remodeling a house:

• Configuration is rearranging furniture.
• CSS is repainting the walls.
• Component overrides are rebuilding part of the room.

Recommended Customization Order

Before overriding a Starlight component, try these approaches in order:

1. Use page frontmatter.
2. Use Starlight configuration in astro.config.mjs.
3. Use custom CSS.
4. Use MDX or Astro components inside your content.
5. Override a Starlight component only when the earlier options cannot solve the problem.

This order keeps your site easier to upgrade and maintain.

Project Structure for Customization

A customized Starlight project might use this structure:

my-starlight-site/
  public/
    favicon.png
    images/
  src/
    assets/
      light-logo.svg
      dark-logo.svg
    components/
      CharacterCard.astro
      LessonObjectives.astro
    overrides/
      SiteTitle.astro
      PageTitle.astro
      Footer.astro
    styles/
      custom.css
    content/
      docs/
        index.md
        getting-started.md
  astro.config.mjs
  package.json

You do not have to use an overrides folder, but it is a clean convention. It makes it obvious which files are replacing Starlight internals.

Level One: Configuration Customization

Many customizations belong in astro.config.mjs. This file controls Astro and Starlight settings.

import { defineConfig } from 'astro/config';
import starlight from '@astrojs/starlight';

export default defineConfig({
  integrations: [
    starlight({
      title: 'My World Bible',
    }),
  ],
});

Use configuration when you want to change official Starlight options such as title, sidebar, logo, social links, page layout behavior, table of contents, or custom CSS registration.

Adding a Logo

Add logo files to src/assets/:

src/assets/light-logo.svg
src/assets/dark-logo.svg

Then configure the logo:

import { defineConfig } from 'astro/config';
import starlight from '@astrojs/starlight';

export default defineConfig({
  integrations: [
    starlight({
      title: 'My World Bible',
      logo: {
        light: './src/assets/light-logo.svg',
        dark: './src/assets/dark-logo.svg',
      },
    }),
  ],
});

If your logo image already contains the site title, you can visually hide the text title while keeping it available for screen readers:

logo: {
  src: './src/assets/logo.svg',
  replacesTitle: true,
}

Customizing the Page Layout with Frontmatter

For a special landing page, use Starlight’s template: splash frontmatter option.

---
title: "World Bible Home"
template: splash
---

# World Bible Home

Welcome to the setting archive.

This is useful for homepages, course landing pages, or large visual index pages. Use this before trying to override layout components.

Customizing the Table of Contents

Starlight normally displays a table of contents based on page headings. For some pages, you may want to reduce or disable it.

---
title: "Landing Page"
tableOfContents: false
---

Use this for pages where the normal right-side page navigation is not helpful, such as a homepage, gallery, or custom index.

Level Two: Custom CSS

Custom CSS is the safest way to change the look of a Starlight site.

Create:

src/styles/custom.css

Register it in astro.config.mjs:

import { defineConfig } from 'astro/config';
import starlight from '@astrojs/starlight';

export default defineConfig({
  integrations: [
    starlight({
      title: 'My Custom Docs',
      customCss: ['./src/styles/custom.css'],
    }),
  ],
});

Now your CSS file can customize theme variables and page styling.

Theme Variables

Starlight exposes CSS custom properties that can be changed in your custom CSS file.

:root {
  --sl-font: system-ui, sans-serif;
  --sl-content-width: 48rem;
  --sl-text-5xl: 3rem;
}

Exact variable names may change as Starlight evolves, so always check the current Starlight CSS and styling documentation when making deep visual changes.

Styling Custom Content Components

If you create your own components, style them with classes in your custom CSS.

/* src/styles/custom.css */
.character-card {
  border: 1px solid var(--sl-color-gray-5);
  border-radius: 0.75rem;
  padding: 1rem;
  margin: 1rem 0;
}

Then use that class in an Astro component:

---
const { name, role } = Astro.props;
---

<aside class="character-card">
  <h2>{name}</h2>
  <p>{role}</p>
</aside>

This approach is safer than overriding Starlight’s built-in UI.

Level Three: Content Components

Before replacing Starlight internals, ask whether you only need a reusable content block.

Examples:

• Character stat card
• Faction summary box
• Lesson objectives box
• Warning callout
• Timeline entry
• World bible metadata panel

These belong in src/components/, not necessarily in Starlight overrides.

Example: Lesson Objectives Component

Create:

src/components/LessonObjectives.astro

Add:

---
const { title = 'Lesson Objectives' } = Astro.props;
---

<aside class="lesson-objectives">
  <h2>{title}</h2>
  <slot />
</aside>

Use it in an MDX page:

---
title: "Markdown Basics"
---

import LessonObjectives from '../../components/LessonObjectives.astro';

# Markdown Basics

<LessonObjectives>
- Understand headings
- Write lists
- Add links
- Add code blocks
</LessonObjectives>

This adds a custom block without changing Starlight itself.

Level Four: Component Overrides

Component overrides are for changing Starlight’s built-in interface. Starlight supports overriding built-in components by pointing component names to your replacement files in the Starlight components configuration option.

starlight({
  title: 'My Custom Docs',
  components: {
    SiteTitle: './src/overrides/SiteTitle.astro',
  },
})

This tells Starlight, “When you would normally render SiteTitle, use my file instead.”

When to Override a Component

Override a Starlight component when you need to change behavior or markup that CSS cannot reasonably change.

Basic Override Setup

Create an override folder:

src/overrides/

Create a replacement component:

src/overrides/SiteTitle.astro

Register it in astro.config.mjs:

import { defineConfig } from 'astro/config';
import starlight from '@astrojs/starlight';

export default defineConfig({
  integrations: [
    starlight({
      title: 'My Custom Docs',
      components: {
        SiteTitle: './src/overrides/SiteTitle.astro',
      },
    }),
  ],
});

Example: Override SiteTitle

A simple custom SiteTitle might look like this:

---
import type { Props } from '@astrojs/starlight/props';
const { siteTitle } = Astro.props;
---

<a class="custom-site-title" href="/">
  <span class="custom-site-title__mark">◆</span>
  <span>{siteTitle}</span>
</a>

Then style it:

.custom-site-title {
  display: inline-flex;
  align-items: center;
  gap: 0.5rem;
  font-weight: 700;
  text-decoration: none;
}

.custom-site-title__mark {
  font-size: 1.25rem;
}

This is useful if you want the site title to have special markup, icon text, or different link behavior.

Important: Check the Override Reference

Do not guess component names. Starlight has an overrides reference that lists the components available to override.

Common kinds of override targets include:

• Header and site title components
• Sidebar-related components
• Page title and content layout components
• Footer components
• Table of contents components
• Search-related components

Component names and APIs can change over time, so always compare your override with the current Starlight implementation.

Extending Instead of Replacing

Sometimes you do not want to fully replace a component. You want to reuse the default component and wrap it with extra markup.

Conceptually, this looks like:

---
import DefaultComponent from '@astrojs/starlight/components/SomeComponent.astro';
---

<div class="custom-wrapper">
  <DefaultComponent {...Astro.props} />
  <p>Extra custom content</p>
</div>

This approach can be safer than rewriting everything from scratch, but the exact import path depends on Starlight’s current exports and documentation.

Common Override Example Ideas

Custom footer

Use this when you want world bible copyright notes, project version, contact links, or deployment metadata.

Custom site title

Use this when the site title should link somewhere special or include custom branding markup.

Custom page title

Use this when you want to display page metadata under titles, such as lesson level, region, character type, or last updated date.

Custom sidebar or table of contents

Use this only when you need different navigation behavior. Sidebar overrides can become complex because they affect how readers move through the entire site.

World Bible Use Cases

For a world bible, component overrides can help make Starlight feel less like generic software documentation.

Lesson Site Use Cases

For a lesson or tutorial site, customizations usually support learning flow.

Example: Page Metadata Display

For lesson or world bible pages, you may want visible metadata:

---
title: "Markdown Basics"
level: "Beginner"
section: "Writing Formats"
status: "Draft"
---

Before overriding Starlight’s page title, consider adding a normal MDX component at the top of the page:

import PageMeta from '../../components/PageMeta.astro';

<PageMeta level={frontmatter.level} section={frontmatter.section} status={frontmatter.status} />

This is easier to maintain than replacing the global title component for every page.

Accessibility Rules for Overrides

When you override built-in UI, you take responsibility for accessibility.

• Keep meaningful links as real <a> elements.
• Keep buttons as real <button> elements when they perform actions.
• Do not remove visible focus styles.
• Keep screen-reader text when replacing logos or titles.
• Use semantic HTML where possible.
• Test keyboard navigation.

Starlight’s default UI is designed with documentation usability in mind. Overrides should preserve or improve that usability.

Upgrade Safety

Component overrides are powerful, but they can be more fragile during upgrades than configuration or CSS.

Best practices:

• Keep overrides small.
• Add comments explaining why each override exists.
• Check the Starlight changelog before upgrading.
• Compare your override with the latest default implementation.
• Prefer wrapping or extending over full replacement when possible.
• Test navigation, search, mobile layout, and keyboard behavior after upgrades.

Common Mistakes

Overriding too soon

If CSS or configuration can solve the problem, use that first.

Copying old component code

Starlight changes over time. If you copy an old default component from a blog post or older project, it may not match your installed version.

Breaking mobile navigation

Header, sidebar, and search overrides can affect small screens. Always test on mobile widths.

Ignoring accessibility

Replacing built-in components can accidentally remove labels, focus behavior, or semantic HTML.

Putting content components in the overrides folder

Reusable content blocks belong in src/components/. Files that replace Starlight internals belong in src/overrides/.

Troubleshooting

The override does not appear

Check that the component name is correct and that the path in astro.config.mjs points to the right file.

The site fails to build

Check imports, component syntax, and whether you used props that are not available to that component.

The override works but styling is wrong

Check whether your CSS file is registered in customCss. Also check whether scoped component styles are taking precedence.

The page layout breaks on mobile

Use browser dev tools to test mobile widths. Built-in Starlight layout components often include responsive behavior you may need to preserve.

Search or navigation behaves strangely

If you overrode search, sidebar, or page navigation components, compare your replacement with the current Starlight default implementation.

Practice Exercise: Safe Customization

Before using overrides, practice with configuration and CSS.

1. Create src/styles/custom.css.
2. Register it with customCss.
3. Add a logo through Starlight config.
4. Create a splash homepage with template: splash.
5. Create a custom MDX component for a lesson objective box.

This gives you a customized site without replacing Starlight internals.

Practice Exercise: First Override

After you are comfortable with safe customization, try a small override.

1. Create src/overrides/SiteTitle.astro.
2. Add simple custom markup for your site title.
3. Register the override in astro.config.mjs.
4. Run npm run dev.
5. Test desktop and mobile layouts.
6. Run npm run build.

Start small. Do not begin by replacing the whole sidebar or page layout.

Full Example Configuration

import { defineConfig } from 'astro/config';
import starlight from '@astrojs/starlight';

export default defineConfig({
  site: 'https://example.com',
  integrations: [
    starlight({
      title: 'World Bible and Lessons',
      logo: {
        light: './src/assets/light-logo.svg',
        dark: './src/assets/dark-logo.svg',
      },
      customCss: ['./src/styles/custom.css'],
      components: {
        SiteTitle: './src/overrides/SiteTitle.astro',
      },
      sidebar: [
        {
          label: 'Start Here',
          items: [
            { label: 'Home', slug: '' },
            { label: 'Getting Started', slug: 'getting-started' },
          ],
        },
        {
          label: 'Lessons',
          autogenerate: { directory: 'lessons' },
        },
        {
          label: 'World Bible',
          autogenerate: { directory: 'world' },
        },
      ],
    }),
  ],
});

Decision Guide

Cheat Sheet

What to Learn Next

• Starlight CSS and theme variables
• Astro component props and slots
• MDX component usage
• Starlight override reference
• Content collections and schemas
• Custom landing pages in Starlight
• Testing Starlight builds before deployment