HTML Contact Form Integration

I need to add a simple contact form to my existing website, styled to match the current look and feel. The form only needs three fields—name, email address, and message—and, once submitted, it should fire a PHP script that emails the collected details to a single recipient address I’ll supply. After a successful send, visitors must be redirected automatically to a separate thank-you page (not just an on-page message). I already have the php POST script and form HTML, just need it to work and CSS it. Please code the form in clean, standards-compliant HTML5, validate inputs server-side in PHP, and keep everything lightweight—no external frameworks are required. Make sure the mail function is dependable on a typical LAMP stack, with clear variables so I can change the destination address later if needed. Deliverables: • Contact-form markup and CSS that blends with my site • PHP handler script with input sanitization and email delivery • Brief read-me outlining where to drop the files and how to change the destination address Once I confirm the form redirects properly and the test message reaches my inbox, we’re done.