We just saw how using AWD is accomplished, using pixels. With RWD and a very simple equation, we can retrofit a site using relative units, in our case percentages. Not to mention it will be a lot easier than using AWD.
Discovered/created by Ethan Marcotte, who coined the term Responsive Web Design, the RWD magic formula is a very simple equation:
(target ÷ context) x 100 = result %
Before we start turning pixels into percentages, we need to see which width our context is going to be.
Our context is going to be the main container of the page .container_12, which has a maximum width of 980px. However, there's a catch involving the main container and the columns that will turn this 980px context into 960px. Notice the 10px left-right padding on the .container_12 section and the 10px left-right margin in the .grid rules:
.container_12 {
width: 980px;
padding: 0 10px;
margin: auto;
}
.grid {
&_1, &_2, &_3, &...