Add support for custom fonts

[valentin0h]

Adds support for custom fonts in GitBook by dynamically generating @font-face rules from user-defined font configurations and preloading the key font sources. It integrates these custom fonts into the layout and OG image generation

[changeset-bot]

🦋 Changeset detected

Latest commit: dedc654

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
gitbook-v2	Patch
gitbook	Patch

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[github-actions]

Summary of the deployments:

Version 1 (production)

Version	URL	Status
Latest commit	https://aed79983.gitbook-open.pages.dev	✅
PR	https://pr2981.gitbook-open.pages.dev	✅

Version 2 (experimental)

Version	URL	Status
Vercel	https://gitbook-v2-okwprsxru-gitbook.vercel.app	✅
Cloudflare	https://90aa6bc2-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	v1	v2
GitBook	https://aed79983.gitbook-open.pages.dev/docs.gitbook.com	https://gitbook-v2-okwprsxru-gitbook.vercel.app/url/docs.gitbook.com
E2E	https://aed79983.gitbook-open.pages.dev/gitbook.gitbook.io/test-gitbook-open	https://gitbook-v2-okwprsxru-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open

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Build	Status	Details	Updated (UTC)
customers-v1 (Inspect)	✅ No changes detected	-	Mar 24, 2025, 7:08 AM
customers-v2 (Inspect)	✅ No changes detected	-	Mar 24, 2025, 7:10 AM
default (Inspect)	👍 Changes approved	2 changed	Mar 24, 2025, 7:11 AM
v2-vercel (Inspect)	✅ No changes detected	-	Mar 24, 2025, 7:12 AM

[emmerich]

Overall looks good, I'm not sure about the use of ReactDOM.preload in SSR though

[SamyPesse]

Looks great 👍