Add skip link to Svelte and SvelteKit sites

[geoffrich]

This PR adds a skip link to svelte.dev and kit.svelte.dev. This allows users navigating by keyboard or with a screen reader to bypass the main navigation, which they would otherwise need to tab through on every page load. It is hidden until it receives focus with the keyboard, at which point it becomes visible.

Points of note:

• I had to set rel="external" on the skip link. Not doing so made it not work the first time and reset focus to the top of the page, not the main content. Not sure if this is expected or a bug in SvelteKit This was a bug, and is no longer needed since latest SvelteKit fixes it
• The skip link needed a z-index set so that it appeared over the main nav.

Screenshot of how it appears when focused:

[vercel]

@geoffrich is attempting to deploy a commit to the Svelte Team on Vercel.

A member of the Team first needs to authorize it.

[benmccann]

Hmm, you shouldn't need rel=external. The behavior you described does sound like a bug

[bluwy]

There's also coincidentally a discussion earlier about the bug as well that might be related.

[vercel]

This pull request is being automatically deployed with Vercel (learn more).
To see the status of your deployments, click below or on the icon next to each commit.

hn – ./sites/hn.svelte.dev

🔍 Inspect: https://vercel.com/svelte/hn/5HdwuEPW9Cdk4FiQhwYNCnbbEvTH
✅ Preview: https://hn-git-fork-geoffrich-skip-link-svelte.vercel.app

svelte-dev – ./sites/svelte.dev

🔍 Inspect: https://vercel.com/svelte/svelte-dev/5wFy1Su2U2iwpFMKifeHyroccw2K
✅ Preview: https://svelte-dev-git-fork-geoffrich-skip-link-svelte.vercel.app

[geoffrich]

This is ready for review now. I was able to remove rel="external" from the skip link after the SvelteKit issue was fixed.

[bluwy]

Works fine for me