Cascading Style Sheets (CSS) is a programming language used to control the visual presentation of websites. While HTML provides the structure and content of web pages, CSS determines how that content appears: colours, fonts, spacing, layouts, animations, and responsive design for different screen sizes. The 'cascading' aspect means styles can be inherited and overridden in a hierarchical manner. Municipal and government websites use CSS to maintain consistent branding, ensure accessibility for users with disabilities, and create user-friendly interfaces. Modern CSS enables sophisticated designs that adapt automatically to phones, tablets, and desktop computers, making government services accessible across all devices.