This sample will demo the difference between how Photoshop renders elements vs how HTML and web browsers render. Export Kit will convert all PSD elements as best as possible, but there are some cases where it is impossible to convert all elements.
Photoshop and HTML are not the same. Photoshop is a single-emulated environment – meaning you can only use Photoshop to view/use Photoshop. Where HTML is a multi-emulated environment – meaning any browser and device can render HTML any way it likes.
IMPORTANT: Different versions of the same browser or device often render very differently also.
This makes HTML the Wild West when it comes to rendering equally on all devices – its virtually impossible. You must have a target range of devices and browsers that you support, then add secondary support for others after.