Lead-Gen Landing Page Build

I want a single, conversion-oriented landing page whose sole purpose is to capture leads. The page should guide visitors toward a clear call-to-action and feed their details straight into a contact form that requests only three fields—name, email address and phone number.

Visual style needs to stay clean, on-brand and fully responsive so it looks great on mobile as well as desktop. Fast load speed is essential, and I’d like the code to be organised for easy future edits. After a visitor submits the form they should see a concise success message or be routed to a thank-you section without leaving the page.

Please hand over all final source files (HTML/CSS/JS or your preferred lightweight framework) along with any assets you create and a brief note explaining where to swap copy or colours if I need to update things later.