HTML/CSS/JS to Custom WordPress Blog

I have a fully-designed site built with plain HTML, CSS and a little vanilla JavaScript that I now want running on WordPress as a true blog. I’d like you to turn the current layout into a clean, responsive custom theme rather than bolting it onto an off-the-shelf template. Every section that exists in the static files should look and behave exactly the same once it sits inside WordPress, but I also need the usual blog features handled from the Dashboard—posts, categories, featured images, widgets and so on—so please wire everything up to native WP functions.

Two extra pieces must be integrated while you work:

• Contact form (I’m happy with a lightweight plugin like Contact Form 7 or an equivalent custom block, as long as it’s GDPR-friendly and easy to edit)
• Social media sharing buttons on posts and pages that respect the current design

The finished deliverable is a zipped installable theme folder plus any child assets, ready for me to drop into /wp-content/themes, activate and go. All styling stays in SASS/SCSS or well-organised CSS, scripts remain unobtrusive, and any functions you add live in functions.php with proper comments so I can follow along later.

I’ll supply the existing codebase and a staging URL as soon as we start. If you can keep page-speed roughly where it is now, ensure the markup remains SEO-friendly, and give me a short walkthrough on how to update colours, fonts or layouts in the future, that will tick every box for this job.