There are two reasons why you aren't getting blue text.
The : is for psuedo-classes, like :focus and :hover (among others). If you want to reference all <b> elements inside a <p> element, you'd do so like this:
Also note the used of the correct closing brace, the brackets MUST correspond to each other, you can't mix and match. The incorrect closing bracket is probably why your CSS only seems to work intermittently.
In future always run your CSS through the CSS Validator, and there's an HTML validator too.
I also don't see a closing brace for your @print styles.