Although style sheets have technically been around in one form or another since the 1970s, it wasn't until around 1996 that they truly became an official part of the web. And although they had a rocky start with browser support, today they are widely used and offer designers a simple way to define style rules for their web pages, saving them from having to type in colors, fonts, and other layout properties over and over again.
CSS for the Newbie - Putting it all Together (Page 2 of 5 )
So now that we know the basic syntax of CSS, let's fool around with it some. Open up a text editor and let's get busy.
Note: Remember that a CSS file is made in a text editor and contains no HTML whatsoever. Also, you must save the file with the .css extention.
Say we want to create a style sheet so that every time the user uses a <p> tag, it automatically changes the attributes of the text within. Here is how we would do it:
p {font-family:verdana;text-align:left;color:blue}
You will note in the above code that we do not place the angle brackets (<>) around our tag. And as I said above, every property is separated by a colon (:). If you wish to change more than one property, then you separate them with the semi-colon (;).
The above code is a little hard to read, and as you can imagine, it would be even harder on the eyes if we were defining an entire style sheet. A better way to write the code would be like this:
p
{
font-family: Verdana;
color: blue;
text-align: left;
}
Note that if we had used a value that consisted of more than one word, like a font name such as Times New Roman, we would encase it in quotes, like so: “Times New Roman”.
Style Sheets 
HTML5 Boilerplate Introduction
