diff --git a/prisma/schema.prisma b/prisma/schema.prisma
index 07c25bd..e6debfe 100644
--- a/prisma/schema.prisma
+++ b/prisma/schema.prisma
@@ -80,7 +80,7 @@ model Booking {
 
   // Organization
   orgName       String
-  orgNumber     String
+  orgNumber     String?
 
   // Invoice address
   address       String
diff --git a/src/app/[locale]/admin/layout.tsx b/src/app/[locale]/admin/layout.tsx
index a3baaaf..982aa9d 100644
--- a/src/app/[locale]/admin/layout.tsx
+++ b/src/app/[locale]/admin/layout.tsx
@@ -26,47 +26,47 @@ export default async function AdminLayout({
 
   return (
     <div className="min-h-screen bg-ink-50">
-      <header className="border-b border-ink-200 bg-white">
+      <header className="border-b border-brand-700 bg-brand-600 text-white">
         <div className="mx-auto flex max-w-6xl items-center justify-between gap-3 px-4 py-3">
           <div className="flex items-center gap-3">
-            <Link href="/admin" className="text-base font-semibold text-ink-900">
+            <Link href="/admin" className="text-base font-semibold">
               {t('title')}
             </Link>
             {session?.user && (
               <nav className="hidden gap-1 sm:flex">
                 <Link
                   href="/admin"
-                  className="rounded-md px-3 py-1.5 text-sm text-ink-600 hover:bg-ink-100"
+                  className="rounded-md px-3 py-1.5 text-sm text-white/80 hover:bg-white/10 hover:text-white"
                 >
                   {t('nav.bookings')}
                 </Link>
                 <Link
                   href="/admin/products"
-                  className="rounded-md px-3 py-1.5 text-sm text-ink-600 hover:bg-ink-100"
+                  className="rounded-md px-3 py-1.5 text-sm text-white/80 hover:bg-white/10 hover:text-white"
                 >
                   {t('nav.products')}
                 </Link>
                 <Link
                   href="/admin/pickup-slots"
-                  className="rounded-md px-3 py-1.5 text-sm text-ink-600 hover:bg-ink-100"
+                  className="rounded-md px-3 py-1.5 text-sm text-white/80 hover:bg-white/10 hover:text-white"
                 >
                   {t('nav.pickupSlots')}
                 </Link>
                 <Link
                   href="/admin/replacements"
-                  className="rounded-md px-3 py-1.5 text-sm text-ink-600 hover:bg-ink-100"
+                  className="rounded-md px-3 py-1.5 text-sm text-white/80 hover:bg-white/10 hover:text-white"
                 >
                   {tr('navTitle')}
                 </Link>
                 <Link
                   href="/admin/settings"
-                  className="rounded-md px-3 py-1.5 text-sm text-ink-600 hover:bg-ink-100"
+                  className="rounded-md px-3 py-1.5 text-sm text-white/80 hover:bg-white/10 hover:text-white"
                 >
                   {t('nav.settings')}
                 </Link>
                 <Link
                   href="/admin/users"
-                  className="rounded-md px-3 py-1.5 text-sm text-ink-600 hover:bg-ink-100"
+                  className="rounded-md px-3 py-1.5 text-sm text-white/80 hover:bg-white/10 hover:text-white"
                 >
                   {t('nav.users')}
                 </Link>
@@ -82,7 +82,10 @@ export default async function AdminLayout({
                   await signOut({ redirectTo: '/admin/login' });
                 }}
               >
-                <button type="submit" className="btn-ghost text-xs">
+                <button
+                  type="submit"
+                  className="rounded-md px-3 py-1.5 text-xs text-white/80 hover:bg-white/10 hover:text-white"
+                >
                   {t('nav.signOut')}
                 </button>
               </form>
diff --git a/src/components/BookingForm.tsx b/src/components/BookingForm.tsx
index f5e1ba9..651a3d0 100644
--- a/src/components/BookingForm.tsx
+++ b/src/components/BookingForm.tsx
@@ -126,7 +126,7 @@ export function BookingForm({
         /^\S+@\S+\.\S+$/.test(email) &&
         phone.trim().length >= 5 &&
         orgName.trim().length >= 2 &&
-        isValidSeOrgNumber(orgNumber) &&
+        (orgNumber.trim() === '' || isValidSeOrgNumber(orgNumber)) &&
         address.trim().length >= 2 &&
         postalCode.trim().length >= 3 &&
         city.trim().length >= 1
@@ -347,7 +347,6 @@ export function BookingForm({
                 />
                 <Field
                   label={t('details.orgNumber')}
-                  required
                   value={orgNumber}
                   onChange={(v) => patch({ orgNumber: v })}
                   placeholder={t('details.orgNumberPlaceholder')}
diff --git a/src/lib/validation.ts b/src/lib/validation.ts
index a7b8908..f202dba 100644
--- a/src/lib/validation.ts
+++ b/src/lib/validation.ts
@@ -14,12 +14,13 @@ export const bookingSubmitSchema = z.object({
   orgNumber: z
     .string()
     .trim()
-    .min(10)
     .max(13)
-    .refine((v) => isValidSeOrgNumber(v), {
+    .refine((v) => v === '' || isValidSeOrgNumber(v), {
       message: 'invalidOrgNumber',
     })
-    .transform((v) => normalizeOrgNumber(v)),
+    .transform((v) => (v === '' ? null : normalizeOrgNumber(v)))
+    .nullable()
+    .optional(),
   address: z.string().trim().min(2).max(200),
   postalCode: z.string().trim().min(3).max(20),
   city: z.string().trim().min(1).max(100),