Rework full-width layout, add support for full-width page option

[zenoachtig]

• site-full-width is applied any time the site needs to grow wider to accommodate a bigger block. It's applied for OpenAPI blocks, fullwidth blocks, and for the (soon to be added) fullwidth page option. It basically signals that some UI should no longer be restricted to the container, but go full width instead.
  • Individual blocks can be set to full-width and expand, while other blocks remain bound to the default centred container.
• page-full-width is applied only when the (soon to be added) fullwidth page option is turned on. It signals that the page's container should be wider.
  • Setting the full-width page option increases the container width from 3xl to screen-2xl.
• Rework the header and footer to have a consistent max-width, equal to the centred container

[changeset-bot]

🦋 Changeset detected

Latest commit: 48f9534

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

This PR includes changesets to release 1 package

Name	Type
gitbook	Minor

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[github-actions]

Summary of the deployments:

Version 1

Version	URL	Status
Latest commit	https://93b2aa93.gitbook-open.pages.dev	✅
PR	https://pr3293.gitbook-open.pages.dev	✅

Version 2

Version	URL	Status
Vercel	https://gitbook-v2-1najkz1sh-gitbook.vercel.app	✅
Cloudflare	https://7878b2fd-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	v1	2v	2c
GitBook	https://93b2aa93.gitbook-open.pages.dev/gitbook.com/docs	https://gitbook-v2-1najkz1sh-gitbook.vercel.app/url/gitbook.com/docs	https://7878b2fd-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.com/docs
E2E	https://93b2aa93.gitbook-open.pages.dev/gitbook.gitbook.io/test-gitbook-open	https://gitbook-v2-1najkz1sh-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open	https://7878b2fd-gitbook-open-v2-preview.gitbook.workers.dev/url/gitbook.gitbook.io/test-gitbook-open

[argos-ci]

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Build	Status	Details	Updated (UTC)
customers-v1 (Inspect)	✅ No changes detected	-	Jun 11, 2025, 11:59 AM
customers-v2 (Inspect)	👍 Changes approved	77 changed	Jun 11, 2025, 11:57 AM
default (Inspect)	👍 Changes approved	4 changed	Jun 11, 2025, 12:02 PM
v2-cloudflare (Inspect)	👍 Changes approved	4 changed	Jun 11, 2025, 12:02 PM
v2-vercel (Inspect)	👍 Changes approved	4 changed	Jun 11, 2025, 11:59 AM

[conico974]

I'm a bit confused here ? Do you want to keep both page-full-width and site-full-width