Custom css only for one content type
use node-type-"node-type-machine-name" class from body, it appears in body, and then apply inherited CSS on child classes or on elements. e.g. if you are using a content type conference use 

.note-type-conference{ 
//style
}


or 

.note-type-conference .any-other-child-class{ 
    //style
    }


open your developer console of browser and check body element it contains many unique and specific classes.