If the basic structure of a site is built using HTML, then CSS determines what it looks like, how and where you see images and other styling elements. Button styles, layouts, colours and more can be customised using CSS.
Cascading Style Sheets (CSS) can control the layout and visual elements of multiple pages at once. CSS brings the freedom of design to websites, for a better user experience. CSS can be integrated with a variety of platforms and platforms, with CSS components in use in most websites today.