The preferences.json file is used to modify behavior of some actions and resolvers of Emmet. This file contains a simple dictionary of key–value pairs.

For example, on “CSS Gradients” there’s description of css.gradient.fallback option which enables fallback background-color value when definition is expanded. To enable it, simply add this key to preferences.json file:

{
    "css.gradient.fallback": true
}

Here’s a list of currently available options: