A `position:fixed` sidebar whose width is set in percentage?

Question

I\'ve successfully used the beautiful Susy grid system to create a responsive layout similiar to the one of WebDesignerWall.com:

What i failed to implement is a

Answer 1

Why don't you just use math? =)

Example html:

 

    

        
This is fixed
    

CSS

.container {
    width: 80%;
    margin: 0 auto;
}

.col {
   float: left;
    width: 33.3333333333%;
}

.fixed {
    position: fixed;
    width: 26.666666666%; /* .container width x .col width*/
}