Add enhanced header to summarize chatbot purpose

[teloon]

This PR adds an enhanced header to the course materials chatbot that clearly explains its purpose and capabilities.

Changes

• Added descriptive title with emoji: 🎓 Course Materials Assistant
• Enhanced subtitle explaining AI-powered course material exploration
• Added detailed description about RAG technology and capabilities
• Made header visible with gradient background and proper styling
• Ensured responsive design for mobile devices

Resolves #4

🤖 Generated with Claude Code

[claude]

Claude finished @teloon's task —— View job

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PR Review: Add enhanced header to summarize chatbot purpose

Todo List:

• Read repository guidelines (CLAUDE.md) - No CLAUDE.md found
• Analyze changed files (frontend/index.html and frontend/style.css)
• Review code quality and best practices
• Check for potential bugs or issues
• Evaluate performance considerations
• Look for security concerns
• Assess test coverage implications
• Provide comprehensive feedback

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🔍 Code Review Summary

This PR successfully enhances the user interface by making the header visible and informative. The changes are well-implemented and follow good practices.

✅ Strengths

1. Improved UX: The header now clearly explains the application's purpose, which greatly improves user onboarding
2. Responsive Design: Proper mobile responsive adjustments in frontend/style.css:689-704
3. Semantic HTML: Uses appropriate HTML elements (h1, p with semantic classes)
4. Consistent Styling: Follows existing CSS variable patterns and design language
5. Good Typography: Implements proper text hierarchy with different font sizes and weights
6. Accessibility: Maintains good contrast and readable font sizes

📋 Code Quality Assessment

HTML Changes (frontend/index.html:15-17):

• ✅ Added emoji to title for better visual appeal
• ✅ Enhanced subtitle with more descriptive text
• ✅ Added informative description explaining RAG technology
• ✅ Proper semantic structure maintained

CSS Changes (frontend/style.css:50-84, 693-704):

• ✅ Header made visible by removing display: none
• ✅ Added attractive gradient background
• ✅ Proper spacing and typography
• ✅ Responsive design considerations
• ✅ Consistent with existing design system

🐛 Potential Issues

Minor Issues Found:

1. Cache Busting: The CSS version is updated to v=9 in frontend/index.html:10, which is good practice
2. Text Overflow: At very small screen sizes, the description text might become cramped - consider adding more padding on mobile

🚀 Performance Considerations

• ✅ Minimal Impact: Changes only add minimal CSS and HTML content
• ✅ No Additional HTTP Requests: No new external resources
• ✅ CSS Efficiency: Uses existing CSS variables and patterns

🔒 Security Assessment

• ✅ No Security Issues: All changes are static HTML/CSS content
• ✅ No User Input: No dynamic content or user input handling
• ✅ XSS Prevention: Only static text content, no risk of injection

🧪 Test Coverage

Observations:

• No automated tests detected in the repository
• Changes are purely presentational and low-risk
• Recommendation: Consider adding basic frontend tests for critical UI components in the future

📱 Cross-Browser Compatibility

• ✅ CSS Variables: Well-supported across modern browsers
• ✅ Flexbox: Excellent browser support
• ✅ Gradient Backgrounds: Widely supported
• ⚠️ Minor: -webkit-background-clip used for text gradient (line 62-64) - consider adding fallback for older browsers

🎯 Recommendations

1. Add fallback for text gradient (optional):

   header h1 {
       color: var(--text-primary); /* fallback */
       background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
       -webkit-background-clip: text;
       -webkit-text-fill-color: transparent;
       background-clip: text;
   }

2. Consider adding meta description for better SEO:

   <meta name="description" content="AI-powered course materials assistant using RAG technology">

✅ Final Assessment

This is a well-executed PR that significantly improves the user experience. The code quality is high, follows best practices, and introduces no security or performance concerns. The responsive design is properly handled, and the changes align well with the existing codebase.

Recommendation: ✅ Approve

The header enhancement provides clear value to users by explaining the application's purpose and capabilities, making it much more user-friendly.

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