Float issues

I’ve just added WP php to the ‘news’ section of an existing site, but for some reason my floats have stopped working! I would SO appreciate if someone could look over my code and see what I’m doing wrong. It *should* style like this: http://primocenter.org/news.htm,
but instead it’s styling like this: http://primocenter.org/test/.

My style sheets are almost identical, except I’ve added h2 and h3 styles to the WP one.

thanks for any help.