type DeepPartial<T> = {
  [P in keyof T]?: T[P] extends object ? DeepPartial<T[P]> : T[P];
};

interface UserConfig {
  theme: {
    primaryColor: string;
    secondaryColor?: string;
  };
  notifications: {
    email: boolean;
    sms: boolean;
  };
  profile: {
    username: string;
    avatarUrl: string;
  };
}

// Example usage:
const partialConfig: DeepPartial<UserConfig> = {
  theme: {
    primaryColor: '#336699'
  },
  notifications: {
    email: false
  }
};

// console.log(partialConfig);