recently I have installed K2, after making some changed in K2 css files I couldn't find any solution for aligning center the title under the categories and sub-categories even changes in the fonts.

paletgraphics.com/index.php/products

trying to make this page like that link :

paletgraphics.com/index.php/imggallery


is there any idea ?

Try going into components -> com_k2 -> css -> k2.css

Around line 379 you should see