Change html header and footer

I am looking for a developer to change the header and footer of my custom-built website.

Platform:
- The current website platform is custom-built via html, css and js.

Design:
- I already have the design ready for the new header and footer.

Responsiveness:
- The header and footer need to be responsive and mobile-friendly.

Ideal skills and experience:
- Experience with custom-built websites
- Proficiency in HTML and CSS
- Knowledge of responsive design and mobile optimization