HTML question

I want to extend the width of the blog entries. Is this where I do it?

#main-wrapper {
line-height: 1.4;
float: $startSide;
padding: 10px 12px;
border-top: solid 1px #fff;
width: 428px;
word-wrap: break-word; /* fix for long text breaking sidebar float in IE */
overflow: hidden; /* fix for long non-text content breaking IE sidebar float */
/* Tantek hack - http://www.tantek.com/CSS/Examples/boxmodelhack.html */
voice-family: "\"}\"";
voice-family: inherit;
width: 404px;
}