CSS, or Cascading Style Sheets, solve an important problem of web development: how to make your web site look nice. Styling your apps makes them more usable and nicer-looking; you can also use CSS to create Responsive Web Design (RWD) - allowing your apps to look good no matter what screen size they are displayed on. CSS is not only about making your app look nice; its spec includes animations and transforms that can enable sophisticated interactions for your apps. The CSS Working Group helps maintain current CSS specifications; you can follow their work at [World Wide Web Consortium's site](https://www.w3.org/Style/CSS/members).
CSS, or Cascading Style Sheets, solve an important problem of web development: how to make your web site look nice. Styling your apps makes them more usable and nicer-looking; you can also use CSS to create Responsive Web Design (RWD) - allowing your apps to look good no matter what screen size they are displayed on. CSS is not only about making your app look nice; its spec includes animations and transforms that can enable sophisticated interactions for your apps. The CSS Working Group helps maintain current CSS specifications; you can follow their work at [World Wide Web Consortium's site](https://www.w3.org/Style/CSS/members).
> Note, CSS is a language that evolves, like everything on the web, and not all browsers support newer parts of the specification. Always check your implementations by consulting [CanIUse.com](caniuse.com).
> Note, CSS is a language that evolves, like everything on the web, and not all browsers support newer parts of the specification. Always check your implementations by consulting [CanIUse.com](https://caniuse.com).
In this lesson, we're going to add styles to our online terrarium and learn more about several CSS concepts: the cascade, inheritance, and the use of selectors, positioning, and using CSS to build layouts. In the process we will layout the terrarium and create the actual terrarium itself.
In this lesson, we're going to add styles to our online terrarium and learn more about several CSS concepts: the cascade, inheritance, and the use of selectors, positioning, and using CSS to build layouts. In the process we will layout the terrarium and create the actual terrarium itself.