How To Add CSS | Types of CSS

CSS (Cascading Style Sheets) is used to style HTML documents, determining how elements are presented on web pages. There are three main ways to include CSS in an HTML document: external, inline, and internal.

Inline CSS

Inline CSS involves applying CSS styles directly to individual HTML elements using the style attribute. This method is useful for applying unique styles to specific elements, but it can make maintenance more challenging, especially for larger projects, as styles are scattered throughout the HTML document.

HTML File (index.html):
<!-- index.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Inline CSS Example</title> </head> <body> <h1 style="color: green;">This is an example</h1> <p style="font-size: 22px;">This is a paragraph.</p> </body> </html>


  1. Quick and easy for small modifications.


  1. Makes HTML cluttered and hard to maintain, especially for larger styles.
  2. Overrides other CSS rules with higher specificity.

Internal CSS

Internal CSS involves writing CSS code within the <style> element in the <head> section of the HTML document. This method is useful when you have unique styles for a specific page and don't want to create a separate CSS file.

HTML File (index.html):
<!-- index.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>Internal CSS Example</title> <style> h1 { color: red; } p { font-size: 20px; } </style> </head> <body> <h1>This is an example</h1> <p>This is a paragraph.</p> </body> </html>


  1. Keeps HTML and CSS somewhat separate.
  2. Applies to the entire document.


  1. Can still bloat the HTML file if styles grow.
  2. Requires editing all HTML files to change styling.

External CSS

External CSS involves placing CSS code in a separate file with a .css extension and linking it to the HTML document using the <link> tag. This method allows you to maintain separation of concerns, keeping HTML and CSS in separate files, which can make maintenance easier, especially for larger projects.

HTML File (index.html):
<!-- index.html --> <!DOCTYPE html> <html lang="en"> <head> <meta charset="UTF-8"> <meta name="viewport" content="width=device-width, initial-scale=1.0"> <title>External CSS Example</title> <link rel="stylesheet" href="styles.css"> </head> <body> <h1>This is an example</h1> <p>This is a paragraph.</p> </body> </html>
CSS File (styles.css):
/* styles.css */ h1 { color: blue; } p { font-size: 18px; }


  1. Most recommended for larger projects.
  2. Complete separation of concerns, improving maintainability.
  3. Styles can be reused across multiple HTML pages.
  4. Improves performance by caching downloaded CSS files.


  1. Requires creating and managing an extra file.
  2. Changes require updates in both CSS and HTML.

Choosing the Right Approach:

Inline CSS Convenience

Inline CSS offers convenience for small edits or styling individual elements differently. It allows quick adjustments without the need for separate files or selectors, making it handy for rapid prototyping or tweaking specific elements on a webpage.

Internal CSS Suitability

Internal CSS is ideal for moderate styling needs within a single page. It provides reusable styles that apply to multiple elements, enhancing consistency and efficiency. This method streamlines styling while keeping the CSS code encapsulated within the HTML document for better organization.

External CSS Advantages

External CSS is essential for global styles, ensuring maintainability and performance. By separating CSS into external files, styles can be easily shared across multiple pages, promoting consistency and reducing redundancy. Additionally, browser caching can improve loading speed, enhancing overall performance for users.

Additional Considerations:

CSS Preprocessors (Sass, Less)

These tools extend CSS by introducing features like variables, nesting, mixins, and functions. They enhance code maintainability and readability by enabling reusable and organized styles. Preprocessor code is compiled to standard CSS before deployment, ensuring compatibility across browsers and platforms.

CSS Modules

CSS Modules address the challenge of style conflicts in large projects by scoping styles to individual components. Each component's CSS is encapsulated, preventing unintended style overrides and enhancing modularity. This approach promotes cleaner codebases and smoother collaboration among developers, particularly in complex web applications.

CSS-in-JS Libraries (styled-components, Emotion)

These libraries enable developers to write CSS directly within JavaScript components. This approach offers dynamic styling capabilities, such as conditional styles based on component state or props. However, it may lead to larger bundle sizes due to inline styles, impacting page load times and performance, particularly in resource-constrained environments.


External CSS is preferred for larger projects to maintain separation of concerns, internal CSS is useful for unique styles on specific pages, and inline CSS is suitable for quick styling of individual elements. The choice between them depends on the project's requirements and the level of organization and maintainability desired.