Programming Language Manuals, Documentation and Complete References

HTML

HTML is the markup structure for web pages which provides developers with a means of laying out web applications using controls, navigation, paragraphs, containers, graphics, images, multimedia, applications, forms and more.
 HTML Manual and Documentation

CSS

CSS is used to style documents, apply animations, transition effects, transformation effects, display logic and much more. It is usually seen at work inside of web documents where it styles HTML elements.
 CSS Manual and Documentation