Use single column layout for Developer Tools section

Author: MantisClone

use-cases/checkout.mdx

@@ -119,21 +119,23 @@ Not sure which approach fits your needs? [See our detailed comparison of integra
 
 ## Developer Tools
 
-<Card 
-  title="Payment Widget Button" 
-  icon="credit-card"
-  href="#"
->
-  **Pre-built React checkout component**
-  
-  Drop-in component for crypto payments—works with Easy Invoice Client IDs or direct API integration.
-  
-  - Wallet connection and payment processing included
-  - Fully customizable styling
-  - Compatible with all integration options above
-  
-  [View demo →](https://checkout.request.network)
-</Card>
+<CardGroup cols={1}>
+  <Card 
+    title="Payment Widget Button" 
+    icon="credit-card"
+    href="#"
+  >
+    **Pre-built React checkout component**
+    
+    Drop-in component for crypto payments—works with Easy Invoice Client IDs or direct API integration.
+    
+    - Wallet connection and payment processing included
+    - Fully customizable styling
+    - Compatible with all integration options above
+    
+    [View demo →](https://checkout.request.network)
+  </Card>
+</CardGroup>
 
 ## When to Use Checkout