I am trying to decide on what to use for "restricting" my web application pages width. First, I am using Bootstrap 3.

In the default Site.css, which is automatically installed by VS 2012 when creating a new ASP.NET project, the class content-wrapper has a rule of max width of 960px. Here is the code:

.content-wrapper {
    margin: 0 auto;
    max-width: 960px;
}

But today many desktops have browsers that allow more than 960px of width (e.g. 1200px). So do you think it is a good practice to follow MS "suggestion" of using only 960px?

Another thing I am thinking of setting is the margin for the body of the page. For example:

   body { margin: 30px }

Do you think it is a good practice to set the margin for the body of pages? And what would be a good number?

TIA for any suggestions.