Frankly, I’m not sure I trust Apple to support this appearance API over time. They’ve been down this road before.<p>It’s kind of funny/sad to see how Apple operates with APIs. None of these concepts are really “new”: they were <i>there</i>, in Carbon, prior to Mac OS 8, in the days when that OS was meant to support really elaborate themes.<p>The original theme APIs were huge, and 3rd parties were expected to adopt them as needed (e.g. using appropriate theme selectors for fonts and background patterns). For about a year, things looked really cool: you could create a great Platinum-esque UI for any custom control, and it would fit right in.<p>Then, they threw it ALL away for Mac OS X, ironically right about the time when an appearance-agnostic API would make a lot of sense. They didn’t even bother to update their API implementation to ease migration: really trivial changes that would have been helpful, like “update the damned font/color/pattern value returned for X to resemble Aqua”, were not done. This meant that an app full of seemingly-appearance-agnostic code would look like <i>crap</i> under Aqua, and you had to <i>rip it all out</i>.<p>And it’s not like Mac OS X didn’t change its look. Heck, for a <i>long</i> time you could find 3rd party app bundles chock full of images that were there <i>just</i> to implement the Apple-Look-and-Feel-of-the-Week, because the SDK didn’t offer <i>any</i> reasonable way to do half of what they came up with.<p>So yeah, <i>14 versions later</i>, the Mac wants to be appearance-agnostic again. Sounds great. My advice: always have the option of doing your own UI as a backup.
I haven't tried the latest macOS beta yet, but I remember a few years back finding a minor bug related this: neither Chrome nor Safari handled appearance / highlight color changes correctly. If I remember correctly, I think changing the value wouldn't be completely reflected on any open page until you either refreshed the page or restarted the app; it was one of those two, but I don't remember which. Funny enough, I think some colors did change correctly, but not all. Admittedly, I tested this out using CSS System Colors, which is sadly deprecated.<p>I vaguely recall finding a few bugs with Finder as well, where if you switched back and forth it wouldn't update all colors correctly. Of course, it worked fine after restarting the app... But if Apple's own apps have bugs relating to this, it wouldn't surprise me if it's a common problem for other third-party apps.<p>Another thing people might wanna try out relating to macOS appearance is going to System Preferences -> Accessibility -> Display, and enabling "Increase contrast". It makes some colors look a bit uglier, but I really love how it makes all UI elements stand out. For anyone that doesn't have macOS, or is too lazy to try it out, here's two comparison pictures:<p>* Default appearance: <a href="https://imgur.com/W93o3Md" rel="nofollow">https://imgur.com/W93o3Md</a><p>* Increased contrast: <a href="https://imgur.com/oocjMPs" rel="nofollow">https://imgur.com/oocjMPs</a><p>A bit tangential... I'm hoping that at some point you can use a media query on the browser to test for this value. For example, there's already prefers-reduced-motion [0] on WebKit. I've definitely seen a GitHub issue at some point suggesting that a similar media query be added for users that prefer higher contrast interfaces, but I can't find it at the moment. Unfortunately when I last checked it didn't seem like there was much interest; as usual, accessibility features seem to take a backseat with many browser vendors.<p>[0] <a href="https://webkit.org/blog/7551/responsive-design-for-motion/" rel="nofollow">https://webkit.org/blog/7551/responsive-design-for-motion/</a>
"Dark Side of the Mac" is a blast from the shareware past... <a href="http://www.poubelle.com/DarkSide.html" rel="nofollow">http://www.poubelle.com/DarkSide.html</a>
There should be a dumbed down version of this page to explain designers (and sometimes managers...) why the app is not using the exact #353535 grey they’ve specified in Sketch.