Improve the visual appearance of the new sale form for better user experience

Enhance UI by adjusting section background colors, border sizes in index.css, and button styles, also update replit.md file.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: dec54137-d5a2-4406-8ad4-5f2f9fb110bf
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/0715008c-7244-40f4-befc-26c014852236/ecc2b161-5a3c-4a56-be92-3bd912beb968.jpg

replit.md

@@ -233,6 +233,9 @@ Preferred communication style: Simple, everyday language.
 - ✅ Improved responsive design for mobile and tablet devices
 - ✅ Modern search interface with clear result counting and active search indicators
 - ✅ Dual export options (PDF and CSV) for regulatory compliance reporting
+- ✅ Enhanced save button with more prominent green color for better visibility
+- ✅ Added subtle background colors to each form category (vendor, product, client, identity)
+- ✅ Optimized border thickness for better balance between visibility and aesthetics
 
 ### Docker Configuration & Cleanup (January 9, 2025)
 - ✅ Complete Docker setup optimized for external PostgreSQL database