not sure its bug but i noticed that ipb_styles.css file is the main CSS file of IP.Board and i think its must be appear in individual like ipb_ie.css. i a mnot sure first time after the upgrade where i saw the ipb_styles.css file and on which position in Look & Feel > Manage Skin Sets & Templates > Manage Templates in IP.Board CSS but i am sure i saw this in under ipb_messenger.css. but i recently upgrade Gallery so the ipb_styles.css file now appear in gallery> ipb_styles.css which look like gallery css file. so i think this file changed their location random if any CSS Template add. its look like Template editor design issue.