added /cookbook/

src/components/HeaderLink.astro

@@ -7,7 +7,7 @@ const { href, class: className, ...props } = Astro.props;
 
 const { pathname } = Astro.url;
 const subpath = pathname.match(/[^\/]+/g);
-const isActive = href === pathname || href === '/' + subpath?.[0];
+const isActive = href === pathname || href === '/cookbook/' + subpath?.[0];
 ---
 
 <a href={href} class:list={[className, { active: isActive }]} {...props}>