scb* classes that any plugin bundling it loaded for everything else to use. Code calling html(), html_link(), set_post_field(), scb_init() or any scb_* helper and relying on WP-PageNavi to provide them must now provide them itself. Another installed plugin may still be supplying them, in which case nothing breaks until that one stops.--wp-commentnavi-border-color and --wp-commentnavi-border-color-current to restyle it. If you copied commentnavi-css.css into your theme, rename your copy to wp-commentnavi.css; the plugin's own file is css/wp-commentnavi.css and the theme override is looked up under the matching name.