how i can change color in form.io?

how i can change color in this buttons? I did not see how :( I'm using form.io

 <FormBuilder
            form={{ display: 'form' }}
            onChange={(schema: any) => console.log(schema)}
            options={{
                builder: {
                    basic: {},
                },
            }}
        />

Solution for this: because properties are not used in form.io, you need to apply custom CSS properties example:

   .btn-primary {
    background-color: #ffffff;
    border-color: #e0e0e0ba;
    color: #000000ff;
    font-size: 12px;
}