According the Wordpress' doc, when we create theme, we need to create style.css file in the same place with other files like header.php, footer.php, however, to make a better organization of files, I put all css files in a sub folder.
Then there comes the problem, when I go to the admin area, Appearance -> Editor, I can not see the sub folder so can not edit those css file in the sub folder.
Please help, thanks.