use `data-scrollignore` rather than being level specific

site/src/routes/docs/_sections.js

@@ -125,7 +125,7 @@ export default function() {
 
 					return `
 						<h${level}>
-							<span id="${slug}" class="offset-anchor" ${level === 4 ? 'data-level=4' : ''}></span>
+							<span id="${slug}" class="offset-anchor" ${level > 3 ? 'data-scrollignore' : ''}></span>
 							<a href="docs#${slug}" class="anchor" aria-hidden="true"></a>
 							${text}
 						</h${level}>`;

site/src/routes/docs/index.svelte

@@ -19,7 +19,7 @@
 
 	onMount(() => {
 		// don't update `active_section` for headings below level 3, see _sections.js
-		const anchors = container.querySelectorAll('[id]:not([data-level="4"])');
+		const anchors = container.querySelectorAll('[id]:not([data-scrollignore])');
 
 		let positions;