Overiding the container css

If you take a look at http://goldenglencreamery.com.c25.sitepreviewer.com/?page_id=5

What we want to redefine “full” to be a lot “bigger” than it is currently defined in the style sheet.

<div class="pin-article span12 full" >

However, the style sheet for the theme has no reference to span12 or full and pin-article doesn’t define a width that we can see.

Adding this custom css has no effect

/* Enter Your Custom CSS Here */
div#container {
  width:90% Important!;
}