Refine type of the classes prop

[ktaletski]

🚀 Feature request

Problem description

Looks like type for the classes prop is too strict. Users should either provide classes for all elements or for none.

classes?: {
    root: string;
    trail: string;
    path: string;
    text: string;
    background: string;
};

Suggested solution

I'd suggest to make all entries optional as from the code they seem to actually be that way.

classes?: {
    root?: string;
    trail?: string;
    path?: string;
    text?: string;
    background?: string;
};

[ktaletski]

I can test it and submit a PR if that works