1. How CSS Works: The Rule Set
CSS works by associating rules with HTML elements. A CSS rule consists of a selector and a declaration block.
Selector: Points to the HTML element you want to style (e.g., h1, p, or .button).
Property: The aspect you want to change (e.g., color, font-size, margin).
Value: The specific setting you want to apply (e.g., blue, 20px, auto).
2. The "Cascading" Concept
The word "Cascading" refers to the way the browser determines which styles to apply when multiple rules overlap. Styles can "cascade" down from a general rule to a more specific one. The browser follows a hierarchy based on:
Importance: Rules marked as !important take priority.
Specificity: A style targeting a specific ID (#header) overrides a general tag selector (header).
Source Order: If two rules have the same weight, the one written last (lower down in the file) is the one that wins.
3. Three Ways to Apply CSS
There are three standard methods for adding CSS to an HTML document:
External CSS: You write your styles in a separate file (e.g., style.css) and link it in the HTML
. This is the most professional method as it allows you to change the look of an entire website by editing just one file.Internal CSS: You place the styles inside a