Safari for windows has been discontinued. And market share is non existent. calc() works in IE9 except when you try to position background images with it. Official Twenty Fourteen theme is using calc().
I believe that they are using iframes so the page is never “really” reloaded.
They do it after the theme is put up for sale, so the reviewers never see that.
For start, because the design is not yours.
you can print it on your dog and it will work!
I would like to add “Ultra Responsive” to the mix. The theme is not just responsive, it’s “ultra” responsive.