diff --git a/app/app.vue b/app/app.vue
index 1032046..e29ccb5 100644
--- a/app/app.vue
+++ b/app/app.vue
@@ -9,12 +9,20 @@
 // 15px, which shifted the entire page content 15px to the left. This prop prevents
 // that unwanted padding injection and layout shift.
 import { ConfigProvider } from 'reka-ui'
+
+// Import cart UI components
+const { isMobile } = useCartUI()
 </script>
 
 <template>
   <ConfigProvider :scroll-body="false">
     <div>
       <NuxtPage />
+
+      <!-- Cart UI: Render appropriate component based on screen size -->
+      <!-- Mobile: Bottom sheet, Desktop: Right sidebar -->
+      <CartSheet v-if="isMobile" />
+      <CartSidebar v-else />
     </div>
   </ConfigProvider>
 </template>
diff --git a/app/components/Cart/CartSheet.vue b/app/components/Cart/CartSheet.vue
index 7a2ae7e..4951f2e 100644
--- a/app/components/Cart/CartSheet.vue
+++ b/app/components/Cart/CartSheet.vue
@@ -27,7 +27,7 @@ async function handleRemoveItem(itemId: string) {
 // Navigate to checkout
 function handleCheckout() {
   close()
-  navigateTo('/kasse')
+  navigateTo('/checkout')
 }
 </script>
 
diff --git a/app/components/Cart/CartSidebar.vue b/app/components/Cart/CartSidebar.vue
index 04ffe42..2d28fea 100644
--- a/app/components/Cart/CartSidebar.vue
+++ b/app/components/Cart/CartSidebar.vue
@@ -27,7 +27,7 @@ async function handleRemoveItem(itemId: string) {
 // Navigate to checkout
 function handleCheckout() {
   close()
-  navigateTo('/kasse')
+  navigateTo('/checkout')
 }
 </script>
 
diff --git a/app/components/MockPayPalButton.vue b/app/components/MockPayPalButton.vue
new file mode 100644
index 0000000..57dc415
--- /dev/null
+++ b/app/components/MockPayPalButton.vue
@@ -0,0 +1,106 @@
+<script setup lang="ts">
+/**
+ * Mock PayPal Button Component
+ *
+ * Simulates a PayPal payment for development/testing purposes.
+ * In production, this would be replaced with the real PayPal SDK integration.
+ *
+ * Features:
+ * - Displays mock PayPal button with branding
+ * - Simulates 2-second payment processing
+ * - Emits success event after "payment" completes
+ * - Shows loading state during processing
+ * - Displays amount to be paid
+ */
+
+interface Props {
+  orderId: string
+  amount: number
+}
+
+const props = defineProps<Props>()
+
+const emit = defineEmits<{
+  success: []
+}>()
+
+const isProcessing = ref(false)
+
+/**
+ * Simulate PayPal payment
+ * In production, this would integrate with PayPal SDK
+ */
+async function handlePayment() {
+  isProcessing.value = true
+
+  try {
+    // Simulate payment processing delay (2 seconds)
+    await new Promise((resolve) => setTimeout(resolve, 2000))
+
+    // In production: Call PayPal API to process payment
+    // const result = await processPayPalPayment(props.orderId, props.amount)
+
+    // Emit success event
+    emit('success')
+  } catch (error) {
+    console.error('Mock payment failed:', error)
+    // In production: Show error message to user
+  } finally {
+    isProcessing.value = false
+  }
+}
+</script>
+
+<template>
+  <div class="space-y-4">
+    <!-- Payment Amount Info -->
+    <div class="flex items-center justify-between p-4 bg-white/5 rounded-lg border border-white/10">
+      <span class="text-white/80">Zu zahlen:</span>
+      <span class="text-xl font-bold text-experimenta-accent">
+        {{
+          new Intl.NumberFormat('de-DE', {
+            style: 'currency',
+            currency: 'EUR',
+          }).format(amount)
+        }}
+      </span>
+    </div>
+
+    <!-- Mock PayPal Button -->
+    <button
+      @click="handlePayment"
+      :disabled="isProcessing"
+      class="w-full relative overflow-hidden bg-[#0070ba] hover:bg-[#005ea6] disabled:bg-[#0070ba]/50 disabled:cursor-not-allowed text-white font-bold py-4 px-6 rounded-lg transition-colors shadow-lg"
+    >
+      <span v-if="!isProcessing" class="flex items-center justify-center gap-3">
+        <!-- PayPal Logo SVG -->
+        <svg
+          class="w-6 h-6"
+          viewBox="0 0 24 24"
+          fill="currentColor"
+          xmlns="http://www.w3.org/2000/svg"
+        >
+          <path
+            d="M20.067 8.478c.492.88.556 2.014.3 3.327-.74 3.806-3.276 5.12-6.514 5.12h-.5a.805.805 0 00-.794.683l-.94 5.96-.267 1.69a.404.404 0 01-.4.342H7.55a.48.48 0 01-.474-.555l.912-5.782.916-5.816a.959.959 0 01.948-.812h1.964c4.332 0 7.299-1.775 8.06-6.145a4.803 4.803 0 00-.808-4.014 6.186 6.186 0 00-1.636-1.293A7.943 7.943 0 0013.784 0H6.732A.959.959 0 005.784.812L2.076 23.235a.48.48 0 00.474.555h3.952a.959.959 0 00.948-.812l.912-5.782h1.74c4.919 0 8.74-2.016 9.965-7.718z"
+          />
+        </svg>
+        <span>Mit PayPal bezahlen (Mock)</span>
+      </span>
+      <span v-else class="flex items-center justify-center gap-2">
+        <div
+          class="animate-spin rounded-full h-5 w-5 border-2 border-white/20 border-t-white"
+        />
+        Zahlung wird verarbeitet...
+      </span>
+    </button>
+
+    <!-- Mock Info -->
+    <div class="text-center">
+      <p class="text-xs text-white/40 italic">
+        Dies ist ein Mock-PayPal-Button für Entwicklungszwecke.
+        <br />
+        Die Zahlung wird simuliert und ist nicht echt.
+      </p>
+    </div>
+  </div>
+</template>
diff --git a/app/pages/kasse.vue b/app/pages/checkout.vue
similarity index 87%
rename from app/pages/kasse.vue
rename to app/pages/checkout.vue
index b4d2af1..5d7677b 100644
--- a/app/pages/kasse.vue
+++ b/app/pages/checkout.vue
@@ -1,14 +1,15 @@
 <script setup lang="ts">
 /**
- * Checkout Page (/kasse)
+ * Checkout Page (/checkout)
  *
  * Features:
  * - Requires authentication (middleware: auth)
  * - Shows CheckoutForm with billing address
  * - Shows CartSummary in right sidebar (desktop) / top (mobile)
- * - Redirects to /warenkorb if cart is empty
+ * - Redirects to homepage if cart is empty
+ * - "Warenkorb bearbeiten" button opens cart sidebar
  * - Creates order on form submit
- * - Redirects to /zahlung?orderId={orderId} after order creation
+ * - Redirects to /payment?orderId={orderId} after order creation
  */
 
 // Type for checkout data (matches server schema)
@@ -30,6 +31,7 @@ definePageMeta({
 })
 
 const { items, total, itemCount, fetchCart } = useCart()
+const { open: openCart } = useCartUI()
 
 // Loading states
 const isLoading = ref(true) // Start as true to prevent premature redirect
@@ -80,7 +82,7 @@ async function handleCheckout(checkoutData: CheckoutData) {
 
     if (response.success) {
       // Redirect to payment page with order ID
-      navigateTo(`/zahlung?orderId=${response.orderId}`)
+      navigateTo(`/payment?orderId=${response.orderId}`)
     }
   } catch (err: any) {
     console.error('Order creation failed:', err)
@@ -113,9 +115,7 @@ async function handleCheckout(checkoutData: CheckoutData) {
 
       <!-- Loading State -->
       <div v-if="isLoading" class="text-center py-12">
-        <div
-          class="animate-spin rounded-full h-12 w-12 border-4 border-white/20 border-t-white mx-auto mb-4"
-        />
+        <div class="animate-spin rounded-full h-12 w-12 border-4 border-white/20 border-t-white mx-auto mb-4" />
         <p class="text-white/60">Lade Warenkorb...</p>
       </div>
 
@@ -134,13 +134,8 @@ async function handleCheckout(checkoutData: CheckoutData) {
           <div class="lg:sticky lg:top-4">
             <!-- Mobile: Show summary at top, Desktop: Show in sidebar -->
             <div class="lg:hidden mb-8">
-              <CartSummary
-                :items="items"
-                :total="total"
-                :loading="isCreatingOrder"
-                @checkout="() => {}"
-                class="hidden"
-              />
+              <CartSummary :items="items" :total="total" :loading="isCreatingOrder" @checkout="() => { }"
+                class="hidden" />
               <!-- Simplified summary for mobile -->
               <Card class="p-4 bg-white/5 border-white/10">
                 <div class="flex items-center justify-between">
@@ -157,12 +152,12 @@ async function handleCheckout(checkoutData: CheckoutData) {
                       }}
                     </p>
                   </div>
-                  <NuxtLink
-                    to="/warenkorb"
+                  <button
+                    @click="openCart"
                     class="text-sm text-experimenta-accent hover:underline"
                   >
                     Bearbeiten
-                  </NuxtLink>
+                  </button>
                 </div>
               </Card>
             </div>
@@ -173,12 +168,9 @@ async function handleCheckout(checkoutData: CheckoutData) {
                 <h2 class="text-xl font-bold text-white mb-4">Deine Bestellung</h2>
 
                 <!-- Items List -->
-                <div class="space-y-3 mb-6">
-                  <div
-                    v-for="item in items"
-                    :key="item.id"
-                    class="flex items-start justify-between gap-3 pb-3 border-b border-white/10"
-                  >
+                <div class="space-y-3 mb-4 divide-y divide-white/10">
+                  <div v-for="item in items" :key="item.id"
+                    class="flex items-start justify-between pt-4 py-2 border-white/10">
                     <div class="flex-1">
                       <p class="text-sm font-medium text-white">{{ item.product.name }}</p>
                       <p class="text-xs text-white/60">
@@ -226,9 +218,7 @@ async function handleCheckout(checkoutData: CheckoutData) {
                       }}
                     </span>
                   </div>
-                  <div
-                    class="flex items-center justify-between pt-3 border-t border-white/20"
-                  >
+                  <div class="flex items-center justify-between pt-3 border-t border-white/20">
                     <span class="text-lg font-bold text-white">Gesamt</span>
                     <span class="text-2xl font-bold text-experimenta-accent">
                       {{
@@ -243,12 +233,12 @@ async function handleCheckout(checkoutData: CheckoutData) {
 
                 <!-- Edit Cart Link -->
                 <div class="mt-6 pt-6 border-t border-white/20">
-                  <NuxtLink
-                    to="/warenkorb"
+                  <button
+                    @click="openCart"
                     class="text-sm text-experimenta-accent hover:underline"
                   >
                     Warenkorb bearbeiten
-                  </NuxtLink>
+                  </button>
                 </div>
               </Card>
             </div>
diff --git a/app/pages/bestellung/bestaetigen/[orderId].vue b/app/pages/order/confirm/[orderId].vue
similarity index 96%
rename from app/pages/bestellung/bestaetigen/[orderId].vue
rename to app/pages/order/confirm/[orderId].vue
index 50f06d0..6e6c24a 100644
--- a/app/pages/bestellung/bestaetigen/[orderId].vue
+++ b/app/pages/order/confirm/[orderId].vue
@@ -1,6 +1,6 @@
 <script setup lang="ts">
 /**
- * Order Confirmation Page (/bestellung/bestaetigen/[orderId])
+ * Order Confirmation Page (/order/confirm/[orderId])
  *
  * Features:
  * - Requires authentication (middleware: auth)
@@ -41,7 +41,7 @@ async function fetchOrder() {
     // Check order status
     if (order.value.status === 'completed') {
       // Order already completed - redirect to success page
-      navigateTo(`/bestellung/erfolg/${orderId.value}`)
+      navigateTo(`/order/success/${orderId.value}`)
       return
     }
 
@@ -61,7 +61,7 @@ async function fetchOrder() {
 
     // Redirect to cart after 3 seconds
     setTimeout(() => {
-      navigateTo('/warenkorb')
+      navigateTo('/cart')
     }, 3000)
   } finally {
     isLoading.value = false
@@ -82,7 +82,7 @@ async function confirmOrder() {
 
     if (response.success) {
       // Redirect to success page
-      navigateTo(`/bestellung/erfolg/${orderId.value}`)
+      navigateTo(`/order/success/${orderId.value}`)
     }
   } catch (err: any) {
     console.error('Failed to confirm order:', err)
diff --git a/app/pages/bestellung/erfolg/[orderId].vue b/app/pages/order/success/[orderId].vue
similarity index 96%
rename from app/pages/bestellung/erfolg/[orderId].vue
rename to app/pages/order/success/[orderId].vue
index 8a233a5..9bc053d 100644
--- a/app/pages/bestellung/erfolg/[orderId].vue
+++ b/app/pages/order/success/[orderId].vue
@@ -1,6 +1,6 @@
 <script setup lang="ts">
 /**
- * Order Success Page (/bestellung/erfolg/[orderId])
+ * Order Success Page (/order/success/[orderId])
  *
  * Features:
  * - Requires authentication (middleware: auth)
@@ -21,6 +21,9 @@ definePageMeta({
 const route = useRoute()
 const orderId = computed(() => route.params.orderId as string)
 
+// Get cart composable to refresh cart state
+const { fetchCart } = useCart()
+
 // Order data
 const order = ref<any>(null)
 const isLoading = ref(false)
@@ -43,9 +46,12 @@ async function fetchOrder() {
       // Redirect to confirmation page if still pending
       if (order.value.status === 'pending') {
         setTimeout(() => {
-          navigateTo(`/bestellung/bestaetigen/${orderId.value}`)
+          navigateTo(`/order/confirm/${orderId.value}`)
         }, 2000)
       }
+    } else {
+      // Order completed successfully - refresh cart to show it's empty
+      await fetchCart()
     }
   } catch (err: any) {
     console.error('Failed to fetch order:', err)
diff --git a/app/pages/zahlung.vue b/app/pages/payment.vue
similarity index 95%
rename from app/pages/zahlung.vue
rename to app/pages/payment.vue
index 34cffc5..9ca4f9d 100644
--- a/app/pages/zahlung.vue
+++ b/app/pages/payment.vue
@@ -1,6 +1,6 @@
 <script setup lang="ts">
 /**
- * Payment Mock Page (/zahlung)
+ * Payment Mock Page (/payment)
  *
  * Features:
  * - Requires authentication (middleware: auth)
@@ -28,7 +28,7 @@ const error = ref<string | null>(null)
 // Redirect to cart if no order ID
 watchEffect(() => {
   if (!orderId.value) {
-    navigateTo('/warenkorb')
+    navigateTo('/cart')
   }
 })
 
@@ -47,7 +47,7 @@ onMounted(async () => {
 
     // Redirect to cart after 3 seconds
     setTimeout(() => {
-      navigateTo('/warenkorb')
+      navigateTo('/cart')
     }, 3000)
   } finally {
     isLoading.value = false
@@ -59,7 +59,7 @@ function handlePaymentSuccess() {
   if (!orderId.value) return
 
   // Redirect to order confirmation page
-  navigateTo(`/bestellung/bestaetigen/${orderId.value}`)
+  navigateTo(`/order/confirm/${orderId.value}`)
 }
 </script>
 
@@ -176,7 +176,7 @@ function handlePaymentSuccess() {
 
         <!-- Back Link -->
         <div class="text-center pt-4">
-          <NuxtLink to="/kasse" class="text-sm text-experimenta-accent hover:underline">
+          <NuxtLink to="/checkout" class="text-sm text-experimenta-accent hover:underline">
             ← Zurück zur Kasse
           </NuxtLink>
         </div>
diff --git a/app/pages/products/[id].vue b/app/pages/products/[id].vue
index 85accfe..f12bf01 100644
--- a/app/pages/products/[id].vue
+++ b/app/pages/products/[id].vue
@@ -100,10 +100,8 @@ const handleAddToCart = async () => {
     <div class="min-h-screen bg-gradient-primary px-4 py-12 md:px-6 lg:px-8">
       <!-- Back Button -->
       <div class="mx-auto mb-8 max-w-container-narrow">
-        <NuxtLink
-          to="/products"
-          class="inline-flex items-center gap-2 text-white/80 transition-colors hover:text-white"
-        >
+        <NuxtLink to="/products"
+          class="inline-flex items-center gap-2 text-white/80 transition-colors hover:text-white">
           <ArrowLeft :size="20" />
           <span>Zurück zur Übersicht</span>
         </NuxtLink>
@@ -142,15 +140,9 @@ const handleAddToCart = async () => {
         <div class="overflow-hidden rounded-2xl border border-white/20 bg-white/10 shadow-glass backdrop-blur-lg">
           <!-- Product Image (no padding, flush with top) -->
           <div class="relative aspect-[16/9] w-full overflow-hidden bg-purple-dark">
-            <img
-              src="/img/makerspace-jk-2025.jpg"
-              :alt="product.name"
-              class="h-full w-full object-cover"
-            />
+            <img src="/img/makerspace-jk-2025.jpg" :alt="product.name" class="h-full w-full object-cover" />
             <!-- Gradient overlay -->
-            <div
-              class="absolute inset-0 bg-gradient-to-t from-purple-darkest/80 via-transparent to-transparent"
-            />
+            <div class="absolute inset-0 bg-gradient-to-t from-purple-darkest/80 via-transparent to-transparent" />
           </div>
 
           <!-- Product Content -->
@@ -178,12 +170,10 @@ const handleAddToCart = async () => {
               <!-- Availability Card -->
               <div class="rounded-xl bg-white/5 p-4 backdrop-blur-sm">
                 <span class="mb-1 block text-xs uppercase tracking-wide text-white/60">Verfügbarkeit</span>
-                <div
-                  :class="[
-                    'flex items-center gap-2 text-xl font-semibold',
-                    product.stockQuantity > 0 ? 'text-green' : 'text-red',
-                  ]"
-                >
+                <div :class="[
+                  'flex items-center gap-2 text-xl font-semibold',
+                  product.stockQuantity > 0 ? 'text-green' : 'text-red',
+                ]">
                   <CheckCircle v-if="product.stockQuantity > 0" :size="24" />
                   <span>{{ product.stockQuantity > 0 ? 'Sofort' : 'Nicht verfügbar' }}</span>
                 </div>
@@ -217,19 +207,13 @@ const handleAddToCart = async () => {
 
             <!-- Action Buttons -->
             <div class="flex flex-col gap-4 sm:flex-row">
-              <Button
-                variant="experimenta"
-                size="experimenta"
-                class="flex-1 relative"
-                :disabled="product.stockQuantity === 0 || isAddingToCart"
-                @click="handleAddToCart"
-              >
+              <NuxtLink to="/products" class="btn-secondary flex-1 text-center">
+                Weitere Produkte ansehen
+              </NuxtLink>
+              <Button variant="experimenta" size="experimenta" class="flex-1 relative"
+                :disabled="product.stockQuantity === 0 || isAddingToCart" @click="handleAddToCart">
                 <!-- Loading spinner -->
-                <Loader2
-                  v-if="isAddingToCart"
-                  :size="20"
-                  class="mr-2 animate-spin"
-                />
+                <Loader2 v-if="isAddingToCart" :size="20" class="mr-2 animate-spin" />
 
                 <!-- Button text -->
                 <span v-if="isAddingToCart">Wird hinzugefügt...</span>
@@ -237,16 +221,10 @@ const handleAddToCart = async () => {
                 <span v-else>In den Warenkorb</span>
               </Button>
 
-              <NuxtLink to="/products" class="btn-secondary flex-1 text-center">
-                Weitere Produkte ansehen
-              </NuxtLink>
             </div>
 
             <!-- Already in cart hint -->
-            <div
-              v-if="isInCart && product.stockQuantity > 0"
-              class="mt-2 text-center text-sm text-white/70"
-            >
+            <div v-if="isInCart && product.stockQuantity > 0" class="mt-2 text-center text-sm text-white/70">
               Dieses Produkt befindet sich bereits in deinem Warenkorb.
             </div>
           </div>
diff --git a/server/utils/cart-helpers.ts b/server/utils/cart-helpers.ts
index 19f043f..c6ad0b4 100644
--- a/server/utils/cart-helpers.ts
+++ b/server/utils/cart-helpers.ts
@@ -1,5 +1,5 @@
 import type { H3Event } from 'h3'
-import { and, eq, inArray } from 'drizzle-orm'
+import { and, eq, inArray, asc } from 'drizzle-orm'
 import { carts, cartItems, products } from '../database/schema'
 
 // Re-export shared types
@@ -89,6 +89,7 @@ export async function getCartWithItems(cartId: string): Promise<CartSummary> {
     with: {
       product: true,
     },
+    orderBy: asc(cartItems.addedAt), // Sort by addedAt to maintain stable order
   })
 
   // Separate available and unavailable items