diff --git a/src/components/PlansSection.tsx b/src/components/PlansSection.tsx
index bb11a8d..c7e26be 100644
--- a/src/components/PlansSection.tsx
+++ b/src/components/PlansSection.tsx
@@ -53,7 +53,7 @@ const PlansSection = () => {
   const [checkoutLoading, setCheckoutLoading] = useState(false);
   
   const { products, isLoading: productsLoading } = useShopifyProducts("product_type:Abonnemang");
-  const { addItem, getCheckoutUrl, isLoading: cartLoading } = useCartStore();
+  const { addItem, getCheckoutUrl, clearCart, isLoading: cartLoading } = useCartStore();
 
   const handleSelectPlan = async (plan: typeof planDetails[0]) => {
     // Find the matching Shopify product
@@ -74,6 +74,9 @@ const PlansSection = () => {
     setSelectedPlan(plan.name);
 
     try {
+      // Clear any existing cart items first for a clean checkout
+      clearCart();
+
       await addItem({
         product: shopifyProduct,
         variantId: variant.id,
diff --git a/src/lib/shopify.ts b/src/lib/shopify.ts
index d262494..9bc0a98 100644
--- a/src/lib/shopify.ts
+++ b/src/lib/shopify.ts
@@ -138,7 +138,29 @@ export const STOREFRONT_PRODUCTS_QUERY = `
 // Cart mutations
 export const CART_QUERY = `
   query cart($id: ID!) {
-    cart(id: $id) { id totalQuantity }
+    cart(id: $id) { 
+      id 
+      totalQuantity
+      checkoutUrl
+      lines(first: 100) {
+        edges {
+          node {
+            id
+            quantity
+            merchandise {
+              ... on ProductVariant {
+                id
+                title
+                price {
+                  amount
+                  currencyCode
+                }
+              }
+            }
+          }
+        }
+      }
+    }
   }
 `;
 
diff --git a/src/stores/cartStore.ts b/src/stores/cartStore.ts
index 2f4d015..1491575 100644
--- a/src/stores/cartStore.ts
+++ b/src/stores/cartStore.ts
@@ -208,15 +208,58 @@ export const useCartStore = create<CartStore>()(
       getCheckoutUrl: () => get().checkoutUrl,
 
       syncCart: async () => {
-        const { cartId, isSyncing, clearCart } = get();
+        const { cartId, isSyncing, clearCart, items } = get();
         if (!cartId || isSyncing) return;
 
         set({ isSyncing: true });
         try {
           const data = await storefrontApiRequest(CART_QUERY, { id: cartId });
-          if (!data) return;
+          if (!data) {
+            set({ isSyncing: false });
+            return;
+          }
+          
           const cart = data?.data?.cart;
-          if (!cart || cart.totalQuantity === 0) clearCart();
+          
+          // Cart doesn't exist or is empty - clear local state
+          if (!cart || cart.totalQuantity === 0) {
+            clearCart();
+            return;
+          }
+
+          // Sync local items with Shopify cart
+          const shopifyLines = cart.lines?.edges || [];
+          
+          // Build a map of Shopify line items by variant ID
+          const shopifyItemsMap = new Map<string, { lineId: string; quantity: number }>();
+          for (const edge of shopifyLines) {
+            const variantId = edge.node.merchandise.id;
+            shopifyItemsMap.set(variantId, {
+              lineId: edge.node.id,
+              quantity: edge.node.quantity
+            });
+          }
+
+          // Update local items to match Shopify state
+          const syncedItems = items
+            .filter(item => shopifyItemsMap.has(item.variantId))
+            .map(item => {
+              const shopifyItem = shopifyItemsMap.get(item.variantId)!;
+              return {
+                ...item,
+                lineId: shopifyItem.lineId,
+                quantity: shopifyItem.quantity
+              };
+            });
+
+          // Update checkout URL if available
+          const checkoutUrl = cart.checkoutUrl ? formatCheckoutUrl(cart.checkoutUrl) : get().checkoutUrl;
+
+          if (syncedItems.length === 0) {
+            clearCart();
+          } else {
+            set({ items: syncedItems, checkoutUrl });
+          }
         } catch (error) {
           console.error('Failed to sync cart with Shopify:', error);
         } finally {