Hi Matt,
This snippet of CSS will show only the current page:
ul.perc-breadcrumb-main li {display:none;}
ul.perc-breadcrumb-main li:last-child {display:inline;}
You would also probably want to remove the separator between the breadcrumbs, which can be done within the “Layout” tab.
If you intend to have more than one instance of the breadcrumb widget, I would recommend adding a root class to the breadcrumb widget (“Style” tab) you wish to limit. That way, you can make the CSS more specific and the above styles will only affect that particular instance.
For example:
.sideNavBreadcrumb ul.perc-breadcrumb-main li {display:none;}
.sideNavBreadcrumb ul.perc-breadcrumb-main li:last-child {display:inline;}