Different routes of your app will often share common UI. Instead of repeating it in each +page.svelte component, we can use a +layout.svelte component that applies to all routes in the same directory.

In this app we have two routes, src/routes/+page.svelte and src/routes/about/+page.svelte, that contain the same navigation UI. Let’s create a new file, src/routes/+layout.svelte...

src/routes/
├ about/
│ └ +page.svelte
├ +layout.svelte
└ +page.svelte

...and move the duplicated content from the +page.svelte files into the new +layout.svelte file. The {@render children()} tag is where the page content will be rendered:

<script>
	let { children } = $props();
</script>

<nav>
	<a href="/">home</a>
	<a href="/about">about</a>
</nav>

{@render children()}

<script lang="ts">
	let { children } = $props();
</script>

<nav>
	<a href="/">home</a>
	<a href="/about">about</a>
</nav>

{@render children()}

A +layout.svelte file applies to every child route, including the sibling +page.svelte (if it exists). You can nest layouts to arbitrary depth.