UI Enhancement – Improve Header Design & Navigation Styling

**Summary:**
The current header for the Fitness Chatbot Project is clean but minimal. We can improve it visually and make it more engaging by aligning it with the project’s overall theme and footer styling.

**Proposed Changes:**

- Add project logo on the left for better branding.
- Apply a color theme consistent with the footer or main site colors for visual harmony.
- Add hover effects (color change or underline animation) to navigation links for interactivity.
- Improve spacing and alignment for better readability.
- add a sticky header so navigation stays visible while scrolling.

**Benefits:**

- Stronger branding and identity.
- Better user experience with clearer navigation cues.
- Visually cohesive theme across header, footer, and main sections.
- Professional, polished look for the project.

**Request:**
Please assign this issue to me so I can start working on the header redesign using HTML and CSS only.