Wrap the last Genesis breadcrumb in a span for styling.

functions.php

<?php

add_filter( 'genesis_build_crumbs', 'gj_wrap_last_breadcrumb', 10, 2 );
/**
 * Wrap the last Genesis breadcrumb in a span for styling.
 *
 * @author Gary Jones
 *
 * @param array $crumbs Existing HTML markup for the breadcrumbs.
 *
 * @return array Amended HTML markup for the breadcrumbs.
 */
function gj_wrap_last_breadcrumb( $crumbs, $args ) {
	// Ensure duplicate and empty crumb entries are handled.
	$crumbs = array_filter( array_unique( $crumbs ) );

	$last_crumb_index = count( $crumbs ) - 1;

	// Some "crumbs" actually contain multiple separated crumbs (i.e. sub-pages)
	// so make sure we're really only getting the last separated crumb
	$crumb_parts = explode( $args['sep'], $crumbs[ $last_crumb_index ] );

	if ( count( $crumb_parts ) > 1 ) {
		$last_crumb_part_index = count( $crumb_parts ) - 1;
		$crumb_parts[ $last_crumb_part_index ] = '<span class="last-breadcrumb">' . $crumb_parts[ $last_crumb_part_index ] . '</span>';
		$crumbs[ $last_crumb_index ] = join( $args['sep'], $crumb_parts );
	} else {
		$crumbs[ $last_crumb_index ] = '<span class="last-breadcrumb">' . $crumbs[ $last_crumb_index ] . '</span>';
	}

	return $crumbs;
}

Great! Thank you a lot for shearing!

Thanks! This saved me a lot of time and trouble!