[Almakos]

finally got it to work (I needed to run chinese books on my Nook STR)

I am using Calibre on mac
so in Preferences->Common Options-> Look & Feel
I've pasted this:

@font-face { 
font-family: "DroidFont", serif, sans-serif; 
font-weight: normal; 
font-style: normal;
src: url('res:///system/fonts/DroidSansFallback.ttf'); 
} 
@font-face { 
font-family: "DroidFont", serif, sans-serif; 
font-weight: bold; 
font-style: normal; 
src: url('res:///system/fonts/DroidSansFallback.ttf'); 
} 
@font-face { 
font-family: "DroidFont", serif, sans-serif; 
font-weight: normal; 
font-style: italic; 
src: url('res:///system/fonts/DroidSansFallback.ttf'); 
} 
@font-face { 
font-family: "DroidFont", serif, sans-serif; 
font-weight: bold; 
font-style: italic; 
src: url('res:///system/fonts/DroidSansFallback.ttf'); 
} 
body { 
   margin-right: 8pt; 
   font-family: 'DroidFont', serif; 
}

taken from here http://nookdevs.com/Font_Changes

there is a wizard icon in front of font sizes I've used that wizard and applied some kind of default and set Input character encoding to UTF-8 for some reason

next I dropped epub files to my calibre library and bulk re-encoded them with my new setting and sent to Nook

next opened my chinese books from nook and characters were all messed up, I entered menu where you manage font styles and sizes and checked Use Publisher Default and finally book is perfectly readable

Thank you guys for your help, I was desperate and already bought a card to root my Nook. seems rooting will wait )))