What determines the width of a div class when it's not defined?

Question

I am trying to resize the sidebar column in this example.

It's currently at 25% (column .3u). I would like to expand it to an equivalent of 26% without shrinking the actual main area (column .9u). The only way I see to accomplish is to increase the width of the container div (class .row). But I don't see the width of that class defined in Chrome's "Inspect Element" view! Nor am I seeing the margins or padding of .row, which would push its contents toward the middle and indirectly set its width.

Am I looking in the wrong place, or is Chrome not the best tool to inspect the CSS for this purpose?

Answer 1

You can clearly see the width is applied to .container class in chrome dev tools.

.container {
  margin-left: auto;
  margin-right: auto;
  width: 1200px;
}