Stop CSS styles to be applied in particular sections of the code

Question

This question may sound a bit weird/novice/stupid. Please bear with me.

The below code is a small portion of a webpage I have created using CSS, HTML and coldfusion.

Answer 1

What about using if else instead of just if to determine which css file you should include? In other words, include styles.css only when part 2 displays. That way, you avoid inheritance and scoping issues altogether.