Personally, I would not name your stylesheet "style.css": this can only lead to confusion and possible conflict.
Other than this, the most likely reason it is not working is that the file is not found at the path specified.
Alternatively, the style rules in your file are being over-written by another stylesheet.
"I'm here to save your life. But if I'm going to do that, I'll need total uninanonynymity
." Me Myself & Irene
Validate your HTML