Integrate Transparent Redirect, a solution for merchants who want to maintain full control over designing and hosting checkout pages while remaining PCI compliant.

You also may need to take these steps: 

• If you're using the PARMLIST parameter with Transparent Redirect, follow the Hosted Checkout Pages configuration instructions. 
• Enable your secure token by logging in to your PayPal Manager account and selecting Service Settings > Hosted Checkout Pages > Set Up >Secuirty Options > Enable Secure Token > Yes. 

PayPal highly recommends that you add scripting to ensure the browser posts all sensitive data directly to the PayPal Gateway server rather than to your website.