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Why is CSS Called CSS?

Published in CSS Fundamentals 3 mins read

CSS is called CSS (Cascading Style Sheets) because its style rules are applied to elements in a "cascading" order, and these rules define the "style" of a web page.

Understanding the Components of "Cascading Style Sheets"

Let's break down each part of the name to fully understand why it's called CSS:

  • Style Sheets: This part refers to the fact that CSS provides a way to define the visual style of HTML elements. This includes aspects like fonts, colors, spacing, and layout. Instead of defining these styles directly within the HTML, CSS allows you to create separate "sheets" of styles that can be applied to multiple HTML pages. This separation of concerns is crucial for maintainability and consistency.

  • Cascading: This is the most distinctive aspect of CSS. The "cascading" nature refers to the order in which styles are applied to HTML elements. Multiple style rules can potentially apply to the same element. CSS uses a set of rules to determine which style takes precedence. These rules include:

    • Importance: Some style declarations (using !important) override others, regardless of specificity.
    • Specificity: Selectors with higher specificity (more specific selectors) take precedence over those with lower specificity. For example, an ID selector is more specific than a class selector, which is more specific than an element selector.
    • Source Order: If two rules have the same specificity, the rule that appears later in the CSS (or in a linked stylesheet) takes precedence. This is why it's called "cascading" – styles "cascade" down, and later rules can override earlier ones.
    • Inheritance: Certain styles are inherited from parent elements to their children. For example, the color property is often inherited.
    • Browser Default Styles: Browsers apply their own default styles to HTML elements. These are the least specific and can be easily overridden by CSS.

Example of Cascading

Consider this HTML:

<p style="color: green;">This is a paragraph.</p>

And this CSS:

p {
  color: red;
}

.highlight {
  color: blue;
}

If the paragraph is modified to include the class like this:

<p style="color: green;" class="highlight">This is a paragraph.</p>

The final color of the paragraph text will be green, since inline styles have higher precedence. If there were no inline style, the text would be blue, as the class selector is more specific than the element selector. If there were no inline style, and no class, it would be red due to the paragraph CSS rule. This demonstrates the concept of cascading, where rules are applied and potentially overridden based on their origin, specificity and order.

Why Cascading is Important

The cascading nature of CSS offers several benefits:

  • Flexibility: Allows for a wide range of styling options and overrides.
  • Maintainability: Enables developers to manage styles efficiently across large websites.
  • Reusability: Promotes code reuse through stylesheets and CSS classes.
  • Control: Provides a structured way to control the presentation of web pages.

In essence, CSS's name directly reflects its purpose and how it functions. It's a system of style rules that are applied in a cascading order, enabling developers to control the presentation of web content effectively.

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