The way a website prints is not necessarily how you want it to look. The good news is you can control it easily by adding a print stylesheet to your Theme.

add_action( 'wp_enqueue_scripts', 'child_print_style' );
/**
 * Add print style sheet.
 *
 * This provides the theme with the functionality to include a
 * print style sheet.
 *
 * @author Jen Baumann
 * @link http://dreamwhisperdesigns.com/?p=1035
 */
function child_print_style() {
	wp_enqueue_style( 'child_print_style', $src = CHILD_URL . '/print.css', 'false', '1.0.0', 'print' );
}

Don’t forget to create a file called print.css in your child theme folder.