Dynamic index signature parameter type

enum Color {
  cyan = 'cyan',
  white = 'white',
  gray = 'gray',
}

type Variants = {
  [style: string]: {[key in Color]: string}
}

const foo: Variants = {
  solid: {
    gray: '...'
  }
}
//error: Type '{ gray: string; }' is missing the following properties from type '{ cyan: string; white: string; gray: string; }': cyan, white

enum Color {
  cyan = 'cyan',
  white = 'white',
  gray = 'gray',
}

type Variants = {
  [style: string]: {[key in Color]: string}
}

const foo: Variants = {
  solid: {
    gray: '...'
  }
}
//error: Type '{ gray: string; }' is missing the following properties from type '{ cyan: string; white: string; gray: string; }': cyan, white