Mermaid - Styling class diagram in markdown

Hello I would styling a class diagram defined with mermaid. I need to integrate this diagram in a markdown document (no css customization).

%%{init: {'theme': 'dark'}}%%
classDiagram

class Company {
    id: string
    cognito_sub: string
    first_name: string
        last_name: string
        phone: Phone
        email: string
        tax_code: string
        birth_date: number
        birth_place: string
        img_url: string
        origin: string
        status: CustomerStatus
        note: Note[]
        created_at: number
        updated_at: number
}

I would change background and border color. I can't use css because I need to integrate this diagram on a Notion document.