Can I change the style applied to the banner?

Yes, you can override the CSS by adding CSS code using this hook:

add_action('brucebanner_banner_head', 'mytheme_brucebanner_add_generated_styles', 11,1);
function mytheme_brucebanner_add_generated_styles($sanitized_get){
  echo '<style>
    /* your style here */
  </style>';
}

You can also remove the styling applied by this plugin by following these steps:

remove_action('brucebanner_banner_head', 'brucebanner_add_generated_styles', 10, 1);