CSS Specificity, CSS Inheritance, and a few more CSS tips
You may have experienced the effects of specificity in a number of ways. Perhaps you have applied a hover effect to a link only to be left scratching your head wondering why it’s not working. Or perhaps you have noticed that if you move a declaration further down in your CSS file it magically seams to work. Both of these examples are caused by CSS specificity, a difficult to understand concept for beginners and pros alike.
If you're using simple CSS documents, you may think that specificity really doesn't matter. But the larger and more complicated your CSS style sheets get, the more conflicts you're going to have.