How do I apply the style of a component to the Facebook Login button of the React-facebook-login?

Question

I’m using the package react-facebook-login to create a Facebook login on a page. It already had a stylized button (component). However when I use the Login button component of the package, it is preconfigured with another style.

Component:

<FacebookLogin
      appId="0000000000000"
      autoLoad={true}
      fields="name,email,picture"
      onClick={this.componentClicked}
      callback={this.responseFacebook}
/>

In the component call there is a param that is called cssClass, however I use styled-components, I tried to use it as follows:

<FacebookLogin 
     textButton={'Entre com Facebook'}
     icon={<FontAwesomeIcon 
            icon={faFacebookF} 
            height={24} 
            color={'#FFF'} 
            style={{marginRight: 15}}
      />}
      cssClass={FacebookButton}
/>

Where the FacebookButton is the stylized component I created. In this case, it doesn’t work, precisely because I’m using the component, and the param gets a class.

How could I seek a class, considering that by using a Styled Component, I do not own it?