CSS Playground, developed by webref.ru, is a free Android application that falls under the Education and Reference category. As the name suggests, it is a tool for learning CSS, one of the most important languages used to design web pages. The app allows users to select values of style properties and see the results instantly on the screen.

CSS Playground comes with a user-friendly interface and a wide range of style properties to choose from, including font size, color, background, margin, padding, and more. The app is an excellent resource for beginners who want to learn CSS and experiment with different styles. Overall, CSS Playground is a handy tool for anyone who wants to improve their CSS skills and design beautiful web pages.