Introduction of CSS/CSS3
Cascading Style Sheets is a style distance language used for describing the presentation of a document written in a luxury language comparable to HTML or XML. CSS is a foundation technology of the World Wide Web, alongside HTML and JavaScript. CSS describes how the basics should be rendered on screen, on paper, in speech, or on other media. It's the utmost beginning web designing language. It's easy to learn and apply. It's the language we use to term an HTML document. CSS describes how HTML fundamentals should be displayed. It allows one to edit the presentation to different types of devices, parallel large screens, small screens, or printers. CSS is independent of HTML and can be used with any XML- grounded luxury language.
What Mainly is CSS/CSS3

Why We Need CSS/CSS3
more code means slower runner speed. And CSS enables you to use lower code. CSS allows you to use one CSS rule and apply it to all circumstances of a certain tag within an HTML document. still, it’s easy to do so with CSS, If you need to change the format of a specific set of runners. There’s no need to fix every individual page. Just edit the corresponding CSS stylesheet and you’ll see changes applied to all the pages that are using that style distance. Responsive web design matters. In the moment’s day and age, web pages must be fully visible and easily passable on all devices. Whether mobile or tablet, desktop, or even smart TV, CSS combines with HTML to make responsive design possible.