You're welcome.
Android background sync: Maybe drop that app's name and a screenshot of the Stay Awake button in this thread: [mobile] Keep screen on button
Note Tabs plugin: Unless you meant the mobile plugin panel, I use this above the editor at minimum height on desktop.
CSS: I've seen mobile app color scheme customization come in two main flavors:
- Theme modes (light, dark, OLED, etc.) and pickers for 1+ accent colors. For example: Material Design apps
- Themes as JSON files that can be swapped and/or edited within the app. For example: KurobaEx and KurobaEx themes
If classes are missing, point them out so others can help. If a desired class doesn't exist, you can probably still select it somehow, and someone with wiki access could also update the class list guide.