Using CSS (Cascading Style Sheets) in web design offers numerous benefits, notably enhanced visual appeal and layout control. CSS allows designers to separate content from presentation, meaning changes in style can be applied universally across a website without altering the underlying HTML structure. This promotes consistency and easier maintenance. CSS also improves website performance by enabling faster loading times through optimized stylesheets. Additionally, responsive design can be achieved with media queries, ensuring that websites function well across various devices and screen sizes.