Requests for comment/Grid system

This document proposes to include a Grid system in MediaWiki.

What is a grid system and why is it needed?
A grid defines a set of guides that help in the layout of visual elements. In this way the available space is divided in several columns and rows where content can be placed.

What kind of grid system?
Optional, Nestable, Proportional, Responsive and Semantic

Proportional
Based on percentages, not on a fixed number of columns.

Responsive
Responsive based on abstract sizes.

Semantic
Grid systems are usually supported by adding classes to HTML elements. Adding layout-related information to the markup can be considered a problem. Using a CSS preprocessor as proposed in LESS RFC will allow to use semantic rich classes instead.