Purpose of CSS for web page styling

Summary

CSS (Cascading Style Sheets) is used to control how HTML content looks when it is rendered in a browser. While HTML structures the document, CSS provides the styling—such as text colors and sizes, layout changes, and visual effects—so you can present web pages with the design and layout you want rather than relying on basic browser defaults. Browsers apply CSS by first converting the HTML into a DOM tree, then collecting CSS rules (from inline styles or external .css files), matching them to elements using selectors, and producing a render tree that is ultimately painted to the screen. Even if you write no CSS, browsers use default stylesheets to keep pages readable, which is why learning CSS is necessary to make websites look better and more intentional.

Key Points

• 1

  CSS is responsible for the look and feel of web pages, controlling how HTML elements are styled.

• 2

  Browsers use default styles when no author-defined CSS is provided, but CSS lets you override and customize that appearance.

• 3

  CSS rules use selectors and declaration blocks (property: value) and are applied to the DOM to create a render tree for painting.