Introduction to CSS

CSS (Cascading Style Sheets) is the language that controls the style and appearance of web pages. With it, we can define colors, fonts, layouts, and many visual elements.

What is CSS?

CSS is a standardized style description language that allows the separation of content and presentation. Thus, HTML is responsible for the structure, while CSS is responsible for the visual appearance.

The CSS Syntax

A CSS rule always consists of two parts: a selector and a declaration block. The selector defines which HTML elements the rule applies to, while the declaration contains property–value pairs.

Here is a simple example that displays all paragraphs in blue:

How to Add CSS?

CSS can be inserted into an HTML document in three ways: inline (directly to the element), internal (in the head section), or as an external stylesheet (in a separate file).

Inline CSS

This example shows how to apply styles directly inside the HTML element.

Internal CSS

This example uses an internal style block placed in the head section.

External CSS

This example attaches a separate stylesheet to the document.

The Benefits of CSS

By using CSS we can create consistent, responsive, and easily maintainable websites. Separating style from content provides greater flexibility.

• Separation of content and presentation.
• Consistent design and appearance across multiple pages.
• Simpler creation of responsive websites.

Tips for Using CSS

Some useful advice that helps in the effective use of CSS:

• Prefer external CSS files for clarity.
• Avoid using too many inline styles, as they make code maintenance difficult.
• Use developer tools in the browser to quickly detect errors.