Improved Responsive Header with Search Feature

[mohammadzali2005]

I improved the Kasper template by making the header fully responsive across devices, redesigning it for a cleaner and more modern look, and adding a search functionality to improve usability.
Key Improvements:

• ✅ Responsive Header: Adjusts seamlessly for mobile, tablet, and desktop screens.
• 🎨 Improved Design: Cleaner layout, better spacing, and modern styling for the header section.
• 🔍 Search Feature: Added a functional search bar to enhance navigation and user experience.
• ⚡ Code Optimization: Simplified CSS and HTML structure for easier maintenance.