The Internet Archive discovers and captures web pages through many different web crawls.
At any given time several distinct crawls are running, some for months, and some every day or longer.
View the web archive through the Wayback Machine.
CSS 2.1 corrects a few errors in CSS2, while removing some CSS2 features (most with poor browser support) and adding other features (most with good browser support and strong demand). CSS 2.1 is intended to replace CSS2, and represents a "snapshot" of CSS features that were implemented interoperably when it was published.