This was created to make everyone understand and learn its concepts, an open-source; its code is a programming language used in website building and website templates. It is used to format the look and format of a web page, to set design features such as basic layout, colors, and fonts. CSS allows for continuity between different web pages on the site and makes webpage development easier and faster. CSS frameworks are used for developing responsive and mobile-friendly websites. This book teaches us the fundamental concepts of CSS and JavaScript and guides us through creating websites and games with it. This book is for anyone who wants to create a website or any 2d and 3d game in HTMl5. After finishing this book, anyone will quickly build their website or game with absolute ease, even if they were utterly oblivious to it before. For making websites you should have at least basic knowledge of CSS for designing also we have full fledge chapter of CSS at last. For making games you should have at least knowledge of JavaScript.