Support prominent search bar style

[zenoachtig]

This PR adds support for the new prominent search bar style, resulting in a bigger search bar in the middle of the header. It also reworks the the sizing and spacing of header items in general, and fixes a small layout issue in the footer.

Screen.Recording.2025-03-13.at.12.10.57.Compressed.mp4

[changeset-bot]

🦋 Changeset detected

Latest commit: 51dfdf1

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

Not sure what this means? Click here to learn what changesets are.

Click here if you're a maintainer who wants to add another changeset to this PR

[github-actions]

Summary of the deployments:

Version 1 (production)

Version	URL	Status
Latest commit	https://1564a0a0.gitbook-open.pages.dev	✅
PR	https://pr2936.gitbook-open.pages.dev	✅

Version 2 (experimental)

Version	URL	Status
Vercel	https://gitbook-v2-5yk4bjsna-gitbook.vercel.app	✅
Cloudflare	https://739f0f3b-gitbook-open-v2-preview.gitbook.workers.dev	✅

Test content

Site	v1	v2
GitBook	https://1564a0a0.gitbook-open.pages.dev/docs.gitbook.com	https://gitbook-v2-5yk4bjsna-gitbook.vercel.app/url/docs.gitbook.com
E2E	https://1564a0a0.gitbook-open.pages.dev/gitbook.gitbook.io/test-gitbook-open	https://gitbook-v2-5yk4bjsna-gitbook.vercel.app/url/gitbook.gitbook.io/test-gitbook-open

[argos-ci]

The latest updates on your projects. Learn more about Argos notifications ↗︎

Build	Status	Details	Updated (UTC)
customers-v1 (Inspect)	👍 Changes approved	138 changed	Mar 14, 2025, 1:59 PM
customers-v2 (Inspect)	👍 Changes approved	139 changed	Mar 14, 2025, 2:01 PM
default (Inspect)	👍 Changes approved	430 changed, 64 added	Mar 14, 2025, 2:03 PM
v2-vercel (Inspect)	👍 Changes approved	430 changed, 64 added	Mar 14, 2025, 2:05 PM