Almost every HTML-to-WordPress service and plugin says “pixel-perfect.” Very few show you a measurement. And most people who have moved a hand-made or AI-made design into WordPress know the feeling: it looks nearly right. The hero is two pixels taller, the cards wrap one breakpoint too early, the menu lost its hover underline, the footer font fell back to Arial.

“Nearly” is the problem. A design is a set of decisions, and every small drift is a decision someone else made. This article is about getting an HTML design onto WordPress without any drift at all —and about how to prove it, with numbers, instead of squinting at two browser tabs.

What “Pixel-Perfect” Should Mean

A useful definition is a testable one: at the same viewport, with the same content, the WordPress page renders the same pixels as the original HTML page. Not “looks the same to me”—the same pixels. That gives you two things you can check:

The pixels: screenshot both pages at the same size and subtract one from the other.…