What can css be use for

Answer 1

Cascading Style Sheets (CSS) is a stylesheet language used to describe the presentation or appearance of a document written in HTML.

The general purpose is basically to control the visual design and color of html tags, however css also controls:

Flexbox and Grid layouts
More Complex Layouts
Advanced Positioning
Visual Effects
Responsiveness
Interactivity

https://developer.mozilla.org/en-US/docs/Web/CSS

Answer 2

https://www.w3schools.com/css/default.asp

I hope this helps; if you really need it

Answer 3

CSS is used for modifying the appearance of webpages and web applications.

It is like being given a car and modifying its exterior body panels to look like a Ferrari Spider, Ford Model T, or a Honda Civic.

HTML - the bones of a site
CSS - the skin of a site
Javascript - the muscle or moving parts of a site