Are there any online tools or software that can optimize my css file? I tried http://www.cssoptimiser.com/ but it does not work.
optimizing anything AUTOMATICALLY with any sort of tool is usually a failure... despite many people's claims to the contrary. It is another exampleof people taking shortcuts that wouldn't be necessary with clean formatting and a understanding of how things work. If you concentrate on class reduction in your HTML, use of verbose semantic classnames (again describing what something is, NOT how it looks) inheretance of properties, cascade order and use of contextual selectors - the need for css optimization should rapidly approach nil. Again, instead of leaning on a tool as a crutch, you are most often better served just trying to do it right in the first place. Of course if you are stuck behind crap like Wordpress or Joomla, or relying on even bigger crutches like dreamweaver or frontpage - by the time you get to your CSS it might already be too late to worry about 'optimization' since that's already thrown out the door for the HTML.
Try this one http://floele.flyspray.org/csstidy//css_optimiser.php , I tried some css coding and I'm satisfied with their optimizer