We’re excited to announce the release of a brand new feature in Ghost themes — Custom Settings.
This feature allows developers to build custom settings into a theme that appear directly in Ghost Admin.
This makes it possible to create themes with built in flexibility, so site owners can make stylistic changes without needing to edit theme files.
Here’s the developer documentation and guidelines:
We’d love to hear your questions and feedback below 
and to see what you’ve been building into your Ghost themes.