The article provides an in-depth exploration of CSS at-rules, categorizing them into general and nesting rules, and discusses their practical applications and browser support. It explains how general rules like @charset, @import, and @namespace should be placed at the top of the stylesheet to define character encoding, import external CSS, and prevent style collisions, respectively. Nesting rules such as @document, @font-face, @keyframes, and @media are highlighted for their roles in page-specific styling, custom font usage, defining CSS animations, and creating responsive designs. The article also touches on experimental features like @property, which aims to address certain CSS issues but lacks widespread browser support. It emphasizes the importance of understanding these rules and checking their browser compatibility to ensure effective implementation in projects.