Its called 'scaling'. There are 1B personal devices and only 1 server. So anything that unloads the server is a good thing?
This is what plugins like Descartes are trying to solve - how do we inform CSS of values on the page which may be different between different browsers or users, or may change on the page after it loads as users interact with it.
http://elementqueries.com/demos/variables.html
Here's an example using EQCSS of accessing JavaScript Variables from CSS - I'd ~LOVE~ to see what CSS you could prepare and send in advance that would produce the same thing.
It can't be done :)