diff --git a/app/[locale]/[slug]/page.tsx b/app/[locale]/[slug]/page.tsx
index 19a8db08b..11db4efc8 100644
--- a/app/[locale]/[slug]/page.tsx
+++ b/app/[locale]/[slug]/page.tsx
@@ -169,7 +169,7 @@ export default async function Page(props: { params: Promise<{ locale: string; sl
       id: r.slug,
       slug: r.slug,
       title: r.frontmatter.title,
-      category: r.frontmatter.category || 'Projekt',
+      category: Array.isArray(r.frontmatter.category) ? r.frontmatter.category[0] : (r.frontmatter.category || 'Projekt'),
       image: r.frontmatter.featuredImage
     }))} />,
   };
diff --git a/components/blocks/CertificatesBlock.tsx b/components/blocks/CertificatesBlock.tsx
index 43fd85710..0616677de 100644
--- a/components/blocks/CertificatesBlock.tsx
+++ b/components/blocks/CertificatesBlock.tsx
@@ -93,7 +93,7 @@ export function CertificatesBlock({ badge, title, description, certificates = de
 
   const itemVariants = {
     hidden: { opacity: 0, y: 20 },
-    show: { opacity: 1, y: 0, transition: { duration: 0.5, ease: 'easeOut' } },
+    show: { opacity: 1, y: 0, transition: { duration: 0.5, ease: 'easeOut' as const } },
   };
 
   if (!isMounted) {
diff --git a/lib/references.ts b/lib/references.ts
index c4c353e6b..202abe5da 100644
--- a/lib/references.ts
+++ b/lib/references.ts
@@ -9,6 +9,7 @@ export interface ReferenceFrontmatter {
   dateString?: string;
   featuredImage?: string | null;
   location: string;
+  category?: string | string[];
 }
 
 export interface ReferenceData {