Now that we can reduce the number of images that we request, why don't we reduce the resources that we use as well? Fewer files means a faster website.

When I started developing websites, I often requested two, three, or even four CSS files from the server. It never even crossed my mind to combine these files into one minified kilobyte-sized file. There isn't much here to do as the concept speaks for itself. When you use an application such as CodeKit or Compass.app, it is even easier to do this.

Your media queries and styles can all be in one file. A good practice is to split up the media queries and the main styles. If you're following the mobile-first methodology, you most probably do your mobile styles first and use the media queries to expand on your design, rather that diminishing your styles, and so on, in media queries.

The negative side of this is that, if you combine too many files, you could delay loading the rest of the website. So, find a balance between combining...