It is possible to create pages that are coded to a single line of text. Yes, starting from the opening XHTML Tag (or HTML if your a coder from the Dark Ages) to the closing document tag. Even your JavaScript, which should be externally called, should be able to co-exist at the single-line level.

Realistically, if one were still coding static pages the concept would likely create more work and effort. However, if your site is dynamic and built upon objects that are easily referenced and re-usable the process is much easier.

Although the savings in bandwidth and server utilization is negligible, if added together the overall savings would be enourmous. Web Site Owners may sneer, but your users will appreciate the download and browser loading efficiencies from a site whose pages represent a single line of code. That includes your stylesheet as well!

The trick is to develop in what is easiest for you, as your web site (or web application) develops and matures tighten it up by defining common terms and layout code to variables and/or templates and making use of external CSS.