OK  i understand now. I've created css/rtl.css and it's loaded into HTML but the file is empty, i double checked that i have saved rtl.css but it's still empty. another thing is (but i am not sure about it) that the order of the CSS should be that rtl.css load last to override the original CSS i see now that it's located in the beginning without using Gzip/cache ,maybe with Gzip/cache it's behave different, i don't know...