38 example CSS interview questions (with sample answers)

By Indeed Editorial Team

Published 14 September 2022

The Indeed Editorial Team comprises a diverse and talented team of writers, researchers and subject matter experts equipped with Indeed's data and insights to deliver useful tips to help guide your career journey.

Cascading Styles Sheets (CSS) is a language that web developers use to style an HTML document and change the appearance of websites. During an interview for a technology role that uses CSS, it's important to demonstrate your knowledge of the language by preparing in advance. Learning some common CSS interview questions recruiters ask can help you feel confident about your interview. In this article, we discuss common CSS interview questions and sample answers you can use to prepare for interviews.

General CSS interview questions

Interviewers test your knowledge of this language's fundamental elements and history by asking general CSS interview questions. Here are some examples of questions you might hear:

  1. Can you define CSS and explain its origin?

  2. What variations of CSS exist, and how many have you used?

  3. Who maintains CSS specifications, and how often do they update them?

  4. What are the different components of a CSS style sheet?

  5. What are the three main methods of integrating CSS on a web page?

  6. What is a CSS framework?

  7. How can you use CSS to centre block elements?

  8. What is a rule set in CSS, and how do you implement one?

  9. What are the main advantages of using CSS over other languages or approaches?

  10. What are the limitations of CSS?

Related: A guide on how to ace an interview (with tips and examples)

Questions that demonstrate your experience with CSS

After general questions, an interviewer may move to assess your working knowledge of CSS and whether you possess the relevant skills to succeed in this role. Here are some examples:

  1. What are pseudo-elements, and why are they useful?

  2. What is a descendant selector?

  3. What is a universal selector?

  4. How do you define an element's dimensions in CSS?

  5. Which property controls background image position?

  6. What web-safe fonts can you name?

  7. What tools can you use to enable browser support?

  8. What are the benefits and drawbacks of using external style sheets?

  9. What are the main differences between CSS grid and Flexbox?

  10. What are the different elements of the CSS box model?

Related: Front end vs back end in web development (plus skills)

In-depth questions

An interviewer may test your in-depth knowledge of advanced CSS techniques and approaches to ensure you meet the requirements for the job. Here are some examples:

  1. What is specificity in CSS, and what are its rules?

  2. What are advanced colours in CSS?

  3. What are image sprites, and how are they useful in CSS?

  4. How can you use media queries for mobile devices?

  5. What syntax do you use to link to external style sheets?

  6. Why would you tween an object in CSS?

  7. How do you use the Z-index function, and what does it do?

  8. What are the advantages of using preprocessors in CSS?

  9. What is the difference between grouping and nesting?

  10. What is the difference between an alternate style sheet and an external style sheet?

Related: 10 essential web developer skills

8 examples of interview questions and answers

It can help to see some common interview questions and strong answers to guide you as you prepare for an interview. Here, we give eight examples of interview questions with sample answers:

1. What are the main differences between CSS and CSS3?

Interviewers commonly ask this question to assess your knowledge of basic CSS and whether you keep up with developments in the language. It demonstrates you understand all versions of CSS rather than backdated ones. This skill is important since most new projects tend to use the latest version available. Give several examples of the main differences between the versions to show you understand how the language works differently.

Example answer: 'CSS3 is a newer, improved version of CSS and is backwards-compatible with the original language. One main difference is it allows you to add animation and text effects, unlike CSS, which relied on JavaScript and JQuery's capabilities. You can split CSS3 into modules, and it also supports media queries for responsive websites. Modern browsers are more likely to support CSS3 over the original language.'

Related: FAQ: what is JavaScript?

2. What are the advantages of using a separate CSS sheet instead of adding it to an HTML document?

By asking this question, an interviewer can assess how broad your web knowledge is. It's an important question because CSS interacts with other languages frequently. The interviewer wants to gauge whether you know how to use CSS alongside HTML and whether you understand what's convenient about it.

Example answer: 'CSS works best to control the page design whereas HTML allows the developer to add and organise content. Using a separate CSS sheet instead of adding it to the HTML document means I can implement style changes to the website more quickly. I can make changes to this sheet rather than having to alter the HTML several times.'

Related: A guide to HTML vs JavaScript (with steps and definitions)

3. What is a CSS selector?

An interviewer may ask this basic question about CSS to test your fundamental knowledge. This question helps them determine whether you can apply changes to the content design using a CSS selector. You can answer by defining a selector and mentioning the various types.

Example answer: 'A CSS selector follows pattern rules that tell the browser which HTML elements to apply the CSS values to. To change specific content, you can use a selector to specify the element you want to change. Some examples include class, universal, ID and group selectors.'

Related: A quick guide on how to edit a website in 4 easy steps

4. What are the differences between inline, embedded and external style sheets?

This question is another common way to establish whether you know the basic elements of CSS. It tells the interviewer you understand how to use different kinds of style sheets.

Example answer: 'Inline, embedded and external style sheets help you style HTML. Inline style sheets apply styles to small selections within the HTML. Embedded style sheets go between the HTML header tags and apply styles to the whole HTML document. An external style sheet is a separate file outside the HTML document that can make changes for an entire page or site.'

Related: How to become a web developer (with roles and salary)

5. What do you know about responsive web design?

Interviewers often think it's important to assess whether you know how to make a website accessible across multiple devices. Ensure you mention how important responsive design is for accessing websites on mobile devices.

Example answer: 'Responsive web design resizes and orients a website automatically to fit the dimensions of a user's device. This design allows people to access websites on computers, laptops, tablets and phones without issue. I use responsive design when writing CSS to provide an optimal user experience across all devices.'

Related: Web design vs graphic design: definition and differences

6. What do you know about graceful degradation?

Interviewers ask this question to see how well you can use CSS to improve a user's experience. They also want to see what you know about browser compatibility. Explain graceful degradation briefly and state how it can increase the number of users for a website.

Example answer: 'Graceful degradation refers to designing a website so it's compatible with current and legacy browsers in addition to smaller screens. It ensures the website is functional, attractive and accessible on as many devices as possible rather than focusing on the latest browser. This compatibility is important to ensure content reaches as many users as possible.'

Related: UI vs UX careers: duties, skills and qualifications

7. What do you know about progressive enhancement?

The interviewer asks this question to establish if you can ensure a positive user experience across multiple browsers. Explain the importance of developing core content first and that the website adds functionality according to the capabilities of the user's browser.

Example answer: 'Progressive enhancement is a developmental approach that focuses on the core webpage content first to build the base user experience. The website then adds functionality to the user experience according to what the user's browser can manage. This approach ensures users can access the core website features even if loading the extra content proves challenging.'

Related: How to become a UX designer (with duties and skills)

8. What are the benefits of file splitting?

File splitting is a valuable tool to help developers manage CSS files effectively. This improved efficiency can help eliminate long loading periods. Use your answer to demonstrate you know how it affects the user experience.

Example answer: 'File splitting refers to splitting CSS code and style sheets into separate files and organising them by component type or site section. This method helps manage the code, so a browser only loads the specific style sheets for the sections a user actively sees and refrains from loading anything else. This selectivity greatly decreases load times and improves the user experience. It also makes it easier for developers to manage and edit files in the future.'

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