Background Image Card

<Box
  sx={{
    px: 4,
    py: 6,
    backgroundImage: 'url(https://source.unsplash.com/random/1024x768?sky)',
    backgroundSize: 'cover',
    borderRadius: 8,
    color: 'white',
    bg: 'gray',
  }}>
  <Heading
    textAlign='center'
    fontSize={[ 5, 6 ]}>
    Background Image
  </Heading>
</Box>