CSS Help

I have turned off all css options and tried to create my own but for some reason there seems to be some style that gets inserted on my web pages and I can’t figure out where it’s coming from:

http://www.forumsys.com/resources/tutorials/identity-management/

The title font size should be 15px but it appears as 12px b/c some style got inserted in the page on line 663

If someone can show me how to remove that, it would be very helpful.

https://ww.wp.xz.cn/plugins/recent-posts-widget-extended/