How do you know an import kept a design? Kerf's test is whether the rendered DOM is the same DOM.
On the Copperline Studio sample (an invented studio's site): 134 of 134 CSS selectors still match after the import, and a screenshot of the WordPress page minus a screenshot of the original, at 1440×900, leaves 0 of 1,296,000 pixels.
The subtraction runs live in your browser on https://kerf.site