CSS is the language for designing the presentation layer of Web pages, through colors, structure, and fonts. It allows the web pages to be responsive to different types of devices and screens. CSS is independent of HTML and can be used with any XML-based markup language.
Python is a high level and object oriented scripting language. It is used as general purpose programming language. It is interpreted and interactive language. It has huge standard of libraries compared to all other languages. Python is dominantly used in Data sciences,Machine Learning,Deep Learning and Artificial Intelligence as a NexGen technology.
Mongodb is an Open Source and Nosql database. It is cross-platform and its document oriented database is written in C++. The Mongodb provides best performance, good availability and auto scaling. The Mongodb is used in Big Data, Content Management System, Mobile and Social Infrastructure, User Data Management and Data Hub.