Fixed Font Size?

Just wondering how do i set a fixed font size in my webpage ?

I mean, if i go to View -> text size and change the size, it wont change ?

Good examples are

When i try to change the text size, it doesnt change… i want that on my website !!!

Anyone have a code or so ? sorry im kind of a newb to CSS and Java !

ps: i use dreamweaver ^ ^ !

tkx for help in advance