Tony Patton focuses on CSS fundamentals and explains how multiple rules for the same element are handled. Multiple rules ensure that there will be no surprises for either you or the user community.

Header code here Navigation bar code here Load the style sheet containing your CSS code. If you do not use separate style sheets, the CSS will be located between the tags at the top of your HTML file.

Ryan Boudreaux covers the basics about CSS specificity hierarchy in an effort to make this tricky concept easier to understand.