This is an old post but I have found the solution for the 1.7 and maybe this will help someone in the future. I spent many hours and this may save time to somone in the future. I share this tip because I believe in paying it forward Thanks member_183063
1) my style sheet styles.css was located in:
skin/frontend/default/default/css/ but your can very depending on theme
2) I modified this sheet to apply my general changes to all my pages in my website.
3) I then created my own custom style sheet in this same folder
4) I went to CMS>Pages and selected the page I wanted to change.
5) I clicked on Design and in the Layout Update XML I entered this bit of code:
6) I flushed my cashe in System>Cache Management
and this should apply your changes to just that page you selected to modify and leave the other pages alone.