https://arstechnica.com/gadgets/2018/03/googles-wear-os-developer-preview-gets-dark-ui-lots-of-battery-savings/

Android Wear showed a bit of life a few weeks ago when it was rebranded to "Wear OS by Google," and today it's getting a new Developer Preview based on Android P. Besides the upgrade to a newer version of Android, there are a few new features outlined in Google's blog post.

First, Google is switching to a default "Dark UI system theme." While Android Wear 1.0 sported Google's usual white background with black text, Android Wear 2.0 did a good job of making everything pretty dark. This change will probably clean up some odds and ends that still had a white background.