White-space in text

Hello, My site is: http://parure-bijouterie.be/ I search for insert the following code : white-space: pre-wrap; but only for articles and pages. Not for all site. They are inherit from body. And when i add the code in the body, all widget and other objet change too. I will only change the code for the content of pages and articles. Can you help me ? Thanks Ps: Sorry for my english.