This document discusses different tools for testing CSS including CSSLint for syntax checking, ResembleJS for regression testing layouts, UnCSS for removing unused selectors, and StyleStats for analyzing CSS statistics. It explains how each tool works and recommends which tools to use based on the size and complexity of projects, considering objectives, budgets, and development priorities. CSSLint and UnCSS are recommended for smaller projects while CSSLint, ResembleJS, UnCSS, and StyleStats are suggested for larger, more complex projects.