Custom Contact Form Integration

I need a fully-functional contact form added to my existing website. The form must collect four fields—Name, Email, Phone Number, and a Message/Inquiry textarea—and send the submission to my chosen address while storing a backup in the site’s database.

I already have a look in mind, so please follow the custom design specifications I will supply (Figma screens and style guide). The finished form should match those visuals pixel-for-pixel, be mobile-responsive, and load quickly on all modern browsers.

Core requirements
• Front-end coded in HTML5/CSS3 with lightweight JavaScript validation for required fields and proper email/phone formats.
• Back-end processing in PHP (or an equivalent you recommend) with secure input sanitisation to prevent spam and injection.
• A success/failure message that inherits my site’s typography and colours.
• Easy-to-edit configuration so I can change the destination email later without touching core code.

Optional extras such as file uploads, reCAPTCHA, or inquiry-type dropdowns are not essential right now, but mention in your proposal if you can wire them in should I choose to expand later.

Deliverable is the live form implemented on my server plus a zipped copy of all source files for my records.