Welcome to the World of Design and Structure!

CSS (Cascading Style Sheets) is the stylesheet language that has become the de facto standard for styling web pages. If HTML is the " skeleton " of a site, defining the meaning of elements, then CSS is its visual essence: " clothing, " skin, makeup, and even plastic surgery of movements.

Brief History: Where Did This Come From?

The language was proposed by Håkon Wium Lie in 1994. Before CSS, developers were forced to use HTML tags like <font> or attributes bgcolor. This turned code into " mush " that was impossible to maintain. CSS solved the main problem: separation of content from presentation.

Why Do We Need CSS Today?

Modern CSS is not just " coloring. " It's a powerful tool that allows:

• Responsiveness: The same site looks different on a smartphone, tablet, and 4K monitor.
• Typography: Control over readability, choice from thousands of web fonts, line-height and kerning settings.
• Grids and Layouts: Creating complex interfaces with Flexbox and Grid.
• Performance: CSS animations often work faster than JavaScript, as they use GPU power.

How Does the Browser " See " Your CSS?

When you open a site, the browser does the following:

1. Loads HTML and builds an element tree (DOM) from it.
2. Loads CSS and builds a style tree (CSSOM).
3. Combines them into a " Render Tree " — a blueprint of what exactly needs to be drawn on the screen.
4. Performs Layout (geometry calculation) and Paint (pixel coloring).