Infinite-Scroll – define selectors for "Core 3.4.2 theme"

hello! please, can someone help me with the selectors. i searching and try for hours, but i dont get it … 🙁

http://www.josefstern.com/wordpress

css file …

http://www.josefstern.com/wordpress/wp-content/themes/core/css/screen.css

thanks!

http://ww.wp.xz.cn/extend/plugins/infinite-scroll/