Website designers have been utilizing CSS (Cascading Style Sheets) for many years now. Over and over again, however, I come across an argument that CSS offers no real advantage and whether you code with it or not is just a matter of preference and habit.
I couldn't disagree more.
If you are looking to improve the presentation of your website, CSS will help you do it more efficiently and effectively. CSS based design offers advantages that table-based layout can't compete with.
if you put # before any css tag, only IE 7 and IE 6 will read that line.
if you put _ before any css tag, only IE 6 will read that line.
example:
width: 560px; /* All other browsers */
#width: 558px; /* IE 6 & 7 */
_width: 557px; /* IE 6 */
just remember to keep this order.