Does jqueryui have CSS rules for normal HTML elements?

As I have understood, jqueryui has 2 sets of things:

• Ready made elements that can be used in developing web apps (like menu, datepicker and so so...)
• CSSs ready to use with the elements talked about before

Now my question is:

Are the CSSs ready to be used for Normal HTML Elements, too? Like forms, ul and ol lists, as, and others?

This way, standard HTML elements' style can be compatible with other jqueryui widgets.

Are there also some ready .half, .third, .full-width classes for divs?

Unfortunately I couldn't get the answer even after reading http://api.jqueryui.com/category/theming, http://api.jqueryui.com/theming/css-framework/ and http://api.jqueryui.com/theming/stacking-elements/.

No, jQuery UI doesn't include anything that you mentioned.

jQuery UI is based on widgets. You call one of those widgets on top of your elements and "let the magic happen".

The only styles that you may use in your application CSS are:

• .ui-helper-hidden: to hide your element;
• .ui-helper-hidden-accessible: to hide your element, but let it be "accessible"
• .ui-helper-reset
• .ui-helper-clearfix: The famous clearfix hack
• .ui-helper-zfix
• All the .ui-icons

About the other styles you mentioned:
For styling other elements like forms, lists and the grid system (the .half, .full & etc part of your question), I'd recommend you to give a try to Twitter Bootstrap, if you already haven't.