Global CSS in NextJS - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import a global CSS file in a Next.js app.

NextJS

import '[1]';

Drag options to blanks, or click blank then click option'

A'./utils/helpers.css'

B'./components/Button.css'

C'./pages/index.css'

D'./styles/global.css'

Attempts:

3 left

💡 Hint

Common Mistakes

Importing CSS files inside components instead of _app.js

Using incorrect relative paths

Trying to import CSS files outside the styles folder

In Next.js, global CSS files are imported in the _app.js or _app.tsx file using a relative path like './styles/global.css'.

2fill in blank

medium

Complete the code to create a custom App component that applies global CSS in Next.js.

NextJS

export default function MyApp({ Component, pageProps }) {
  [1]
}

Drag options to blanks, or click blank then click option'

Areturn <div>{Component}</div>;

Breturn <Component />;

Creturn <Component {...pageProps} />;

Dreturn pageProps;

Attempts:

3 left

💡 Hint

Common Mistakes

Not passing pageProps to Component

Wrapping Component incorrectly

Returning pageProps directly instead of JSX

The custom App component must return the page component with its props using <Component {...pageProps} /> to render pages correctly.

3fill in blank

hard

Fix the error in this _app.js file by completing the import statement for global CSS.

NextJS

import [1] from 'next/app';
import './styles/global.css';

export default function MyApp({ Component, pageProps }) {
  return <Component {...pageProps} />;
}

Drag options to blanks, or click blank then click option'

AApp

BReact

CuseState

DComponent

Attempts:

3 left

💡 Hint

Common Mistakes

Importing React instead of App

Using wrong import names

Not importing anything from 'next/app'

To extend the default App in Next.js, you import App from 'next/app'. This is needed if you customize the App component class.

4fill in blank

hard

Fill both blanks to correctly import and use global CSS in a Next.js app.

NextJS

import [1] from 'next/app';
import [2];

export default function MyApp({ Component, pageProps }) {
  return <Component {...pageProps} />;
}

Drag options to blanks, or click blank then click option'

AApp

B'./styles/global.css'

C'./components/button.css'

DReact

Attempts:

3 left

💡 Hint

Common Mistakes

Using component CSS instead of global CSS

Wrong import names or paths

Missing curly braces for named imports

You import App from 'next/app' if extending it, and import the global CSS file with its relative path.

5fill in blank

hard

Fill all three blanks to create a working _app.js file that applies global CSS in Next.js.

NextJS

import [1] from 'next/app';
import [2];

export default function [3]({ Component, pageProps }) {
  return <Component {...pageProps} />;
}

Drag options to blanks, or click blank then click option'

AApp

B'./styles/global.css'

CMyApp

DReact

Attempts:

3 left

💡 Hint

Common Mistakes

Naming the function incorrectly

Not importing global CSS properly

Missing or wrong import from 'next/app'

The default export function is usually named MyApp. You import App from 'next/app' if needed, and import the global CSS file by its path.

Practice

1. In Next.js, where should you import your global CSS file to apply styles across the entire app?

easy

A. In app/layout.js or pages/_app.js

B. In every individual component file

C. Inside public folder

D. In next.config.js

Solution

1. Step 1: Understand global CSS import location

   Global CSS must be imported once at the top-level layout or app file to apply styles app-wide.

2. Step 2: Identify correct files for global CSS import

   Next.js uses app/layout.js in the new app directory or pages/_app.js in the pages directory for this purpose.

3. Final Answer:

   In app/layout.js or pages/_app.js -> Option A

4. Quick Check:

   Global CSS import location = A [OK]

Hint: Global CSS imports go only in app/layout.js or pages/_app.js [OK]

Common Mistakes:

• Importing global CSS in every component causes errors
• Placing CSS files in public folder expecting auto-import
• Trying to import CSS in next.config.js

2. Which of the following is the correct syntax to import a global CSS file named styles.css in app/layout.js?

easy

A. import styles from './styles.css';

B. import './styles.css';

C. require('./styles.css');

D. link rel='stylesheet' href='./styles.css';

Solution

1. Step 1: Recall global CSS import syntax in Next.js

   Global CSS files are imported without assigning to a variable, just using import './filename.css';.

2. Step 2: Evaluate each option

   import styles from './styles.css'; tries to import as a module which is for CSS modules, not global CSS. require('./styles.css'); uses CommonJS require which is not standard in Next.js ES modules. link rel='stylesheet' href='./styles.css'; is HTML syntax, not JavaScript import.

3. Final Answer:

   import './styles.css'; -> Option B

4. Quick Check:

   Global CSS import syntax = D [OK]

Hint: Use plain import './filename.css'; for global CSS [OK]

Common Mistakes:

• Using import with variable for global CSS
• Using require() instead of import
• Trying to add <link> tags inside JS files

3. Given this app/layout.js snippet:

import './globals.css';
export default function RootLayout({ children }) {
  return <html><body>{children}</body></html>;
}

If globals.css sets body { background-color: lightblue; }, what will be the background color of the page?

medium

A. White (default background)

B. Black

C. Transparent

D. Lightblue

Solution

1. Step 1: Understand global CSS effect

   Importing globals.css in app/layout.js applies styles globally, including the body background color.

2. Step 2: Check CSS rule impact

   The CSS rule body { background-color: lightblue; } sets the page background color to lightblue.

3. Final Answer:

   Lightblue -> Option D

4. Quick Check:

   Global CSS body background = B [OK]

Hint: Global CSS affects body styles if imported in layout [OK]

Common Mistakes:

• Thinking global CSS won't apply without explicit class
• Assuming default white background overrides CSS
• Confusing local CSS modules with global CSS

4. You added import './globals.css'; inside a React component file instead of app/layout.js. What problem will you most likely face?

medium

A. Next.js build error about global CSS import location

B. CSS styles will apply only to that component

C. No styles will apply anywhere

D. Styles will load twice causing duplication

Solution

1. Step 1: Recall Next.js global CSS import rules

   Next.js requires global CSS to be imported only in app/layout.js or pages/_app.js. Importing elsewhere causes errors.

2. Step 2: Identify error behavior

   Importing global CSS inside a component triggers a build error stating global CSS cannot be imported from non-top-level files.

3. Final Answer:

   Next.js build error about global CSS import location -> Option A

4. Quick Check:

   Global CSS import location error = A [OK]

Hint: Global CSS import outside layout causes build error [OK]

Common Mistakes:

• Importing global CSS in components expecting scoped styles
• Ignoring build errors and expecting styles to work
• Confusing global CSS with CSS modules

5. You want to set a global font and base color for your Next.js app. Which approach correctly applies these styles globally and ensures they affect all pages?

hard

A. Use CSS modules in each component to set font and color

B. Add inline styles to each page component separately

C. Create globals.css with font and color styles, then import it once in app/layout.js

D. Add a <style> tag with font and color in pages/index.js only

Solution

1. Step 1: Understand global styling needs

   Global fonts and colors should be set once to apply app-wide, not repeated per page or component.

2. Step 2: Choose correct global CSS usage

   Creating a globals.css file with base styles and importing it once in app/layout.js ensures consistent global styles.

3. Final Answer:

   Create globals.css and import it once in app/layout.js -> Option C

4. Quick Check:

   Global base styles = C [OK]

Hint: Put base styles in globals.css and import once in layout [OK]

Common Mistakes:

• Using inline styles repeatedly instead of global CSS
• Relying on CSS modules for global styles
• Adding styles only on one page expecting global effect