In the past, Apple’s two operating systems were distinct islands. The system that ran the Mac and the system that ran the mobile devices had a strikingly different visual appearance, and what happened on each one usually stayed there. Now, with Yosemite, the Mac shares the iPhone’s overall aesthetic, with many icons across the two platforms bearing a striking similarity.

The result is a blissful reduction in cognitive load. As you switch from one kind of machine to the other, buttons and other interface commands generally look the same, so there’s less guessing what happens when you press each one. If you’re familiar with the Share button on your iPhone — an inscrutable rectangle with an upward arrow — its appearance on your Mac will make perfect sense. In Finder, you click Share to mail a document or post a photo to Facebook. In Safari, click Share to tweet a link. Many buttons work the same way; across devices, Apple’s hardware and software now usually do just what you think they will do.

Until they don’t. Apple’s ecosystem is now so integrated that the places that haven’t yet been meshed together stand out starkly and annoyingly. Some of the Mac’s icons now look unnecessarily different from those on iOS devices, sometimes so different that it seems as if the designers were being malicious. In iOS, the Messages app icon is green and white. On the Mac, it’s blue and white. On the new iPhones, the Power button is on the right side of the device. On the new iPads, it’s at the top. These aren’t huge flaws, but Apple is a company obsessed with detail, and these details are off.

The most obvious effort to promote integration between mobile devices and the Mac is a set of features Apple calls Continuity. Broadly, they allow you to share resources like your cellular data connection between your Mac and your phone, and also to pick up where you left off as you flit from phone to tablet to computer. At first blush, this might not sound novel. Most phones, including the iPhone, have long had the ability to share their connections with computers. Google already lets you sync your data across devices; you can pull up the Chrome tabs you opened on your phone this morning on your PC tonight. And a variety of third-party programs, Dropbox most prominently, allow you to share files.