reação opacidade de imagem de fundo

// Basic idea is to create a outer and inner div. 
// Header(outer div) will hold an image, while content(inner) 
//will have a opacity
const styles = {
  header: {
    backgroundImage: `url(${background})`,
    height: '100vh',
    backgroundPosition: 'center',
    backgroundRepeat: 'no-repeat',
    backgroundSize: 'cover'
  },

  content: {
    height: '100%',
    width: '100%',
    backgroundColor: 'rgba(0, 0, 0, 0.5)',
  }
}

<div style={styles.header}>
  <div style={styles.content}>
     Portfolio
  </div>
</div>
aso