Controlling the specificity of CSS Modules in a Next.js App

CSS Modules in Next.js provide locally scoped styling with better control over CSS specificity, helping prevent style conflicts in component-based applications.

• Generate unique class names for component-level styling.
• Avoid conflicts with other components or third-party libraries.
• Improve control over CSS specificity in large applications.
• Can be combined with component hierarchies for better style organization.
• Support dynamic styling using scoped variables.

Steps to Create Next.js application

Create the New Next.js Application by following the below commands in the VS code terminal.

npx create-next-app css-module-hierarchy
cd css-module-hierarchy

Project Structure

This project structure organizes a Next.js application into clear, purpose-driven folders to improve scalability, maintainability, and code clarity.

• .next/ : Auto-generated build output by Next.js.
• components/ : Reusable UI components (e.g., ProfileCard.js).
• pages/ : Defines application routes (e.g., index.js).
• styles/ : Contains global styles and CSS Modules.
• utils/ : Utility/helper files (e.g., scopedVariables.js for shared logic).
• node_modules/ : Installed project dependencies.
• next.config.js : Next.js configuration file.
• package.json / package-lock.json : Project metadata and dependency versions.

[Approach 1]: Combining CSS Modules and Component Hierarchies

This approach controls CSS Module specificity by leveraging the natural component hierarchy in a Next.js application.

• Each component is paired with its own CSS Module.
• Styles are scoped to the component, preventing leakage.
• Parent–child structure helps manage layout and styling clearly.
• Ensures better specificity and isolated styling across the app.

Run the application by executing the below command in the terminal

npm run dev

Output:

Syntax

.button {
 /* Button styling */
}
const Button = ({ children }) => {
 return <button className={styles.button}>
 {children}
 </button>;
};

[Approach 2]: Using Dynamic Styling with Scoped Variables

This approach uses dynamic styling with scoped variables to create flexible and isolated component styles in a Next.js application.

• Styles are defined in a JavaScript utility (scopedVariables.js) using CSS variables.
• Component styles (e.g., ProfileCard) are controlled dynamically through props.
• CSS variables enable dynamic color and style changes.
• Ensures component-specific, isolated styling without conflicts.

Run the application by executing the below command in the terminal

npm run dev

Output:

Syntax

const generateScopedStyles = (componentName, variableValue) => {
 return `
 .${componentName} {
 --custom-variable: ${variableValue};
 /* Other styles using the custom variable */
 }
 `;
};
export default generateScopedStyles;