The Twitter Bootstrap site reads as follows:

The default and simple 940px-wide, centered layout for just about any website or page provided by a single <div class="container">.

Quote from http://twitter.github.com/bootstrap/scaffolding.html#layouts

That's exactly what I have in my HTML but when I inspect the element, I see this CSS apply to it:

.container, .navbar-fixed-top .container, .navbar-fixed-bottom .container {
    width: 1170px;
}

By the way, if I override that CSS rule by adding...

div.container{
  width:940px;
}

Then the elements inside the div.container are wider than the div.container itself and look out of place.

So, why is the Twitter Bootstrap "fixed" layout NOT fixed? and how can I make it fixed?