I've been a web developer for over 20 years, and I've created/coded PHP-based templates—like WordPress themes—for a good portion of that time.
I will create an exact duplicate of your existing site, but in WordPress. A custom WordPress site from your existing HTML/CSS website.
If you prefer to do your own website updates, and would like the ability to add new content—new posts and pages, new images, etc.—then turning your HTML/CSS website into a WordPress site so you don't have to hire someone every single time you want to revise something on, or add something to, your website is definitely the answer.
At no additional cost, I will also include the addition of a blog and set up your first post (a single post index and one blog entry page) so you'll be giving your site an upgrade!
On the front end, no one will notice the difference, aside from the addition of the blog, because it will look just like it used to. Under the hood, you'll be able to edit your own site content any time you want, as many times as you want, and save yourself money in the long run!
This covers up to 20 hours of development time—or a basic website of 5 – 8 simple web pages, plus a home page, and a blog page and index… whichever comes first. I will supply you with a zip of the PHP theme files.