/**
 * Add Allowed HTML Tags
 *
 * @param array $allowedtags Allowed Tags.
 *
 * @return array
 */
function custom_allowed_html( $allowedtags ) {
	$allowedtags['div'] = array_merge(
		isset( $allowedtags['div'] ) ? $allowedtags['div'] : array(),
		array(
			'style' => true,
		)
	);

	return $allowedtags;
}
add_filter( 'wp_kses_allowed_html', 'custom_allowed_html', 100 );