Top 70+ CSS Interview Questions & Answers for All Experience Levels for 2025

Preparing for a technical interview requires focused practice, especially when it comes to CSS. Focus on core topics such as the box model, Flexbox, and grid layouts. Also, explore practical applications such as responsive designs, cross-browser compatibility, and performance optimization. Don’t forget CSS animations, transitions, and mobile-first design principles.

By refining these key areas, you’ll build a strong CSS foundation, improve your problem-solving skills, and be ready to tackle interview challenges with confidence. This blog will cover the top CSS interview questions categorized by beginner, intermediate, and expert levels to help you prepare effectively. Let’s jump in and get you ready to ace your interview.

CSS Interview Questions & Interview Rounds: A Quick Guide

CSS interview questions test your understanding of styling concepts and your ability to apply them in practice. Expect theoretical questions, hands-on coding tasks, and problem-solving challenges. The interview rounds assess your technical knowledge, creative approach to design, and efficiency with CSS. Here's a breakdown of what to expect.

1. Initial Screening (Phone/Online Round)

In the initial round, you'll be asked basic CSS interview questions to test your understanding of fundamental concepts, such as CSS syntax, selectors, and the box model. These CSS interview questions assess your grasp of core CSS properties and layout techniques.

2. Technical Round – Theoretical CSS Interview Questions

The technical round focuses on more complex CSS topics like positioning, z-index, opacity, and media queries. Be prepared to explain CSS functions, layout control, and differences between properties such as inline-block vs block.

3. Coding Round – Practical Application

This round tests your ability to apply CSS in practical scenarios. You’ll be asked to implement a webpage layout, solve CSS-related issues, and use layout techniques like Flexbox and Grid. The efficiency and clarity of your code will be evaluated.

4. Design Round – Problem Solving & Creativity

You will be given design tasks like creating grids or navigation bars, with a focus on creativity and user experience. Expect to solve problems related to cross-browser compatibility, pixel-perfect designs, and advanced CSS features like animations.

5. Discussion on Best Practices and Optimization

This round covers CSS best practices and optimization. You'll discuss techniques like modular CSS, BEM, and performance strategies. Interviewers want to see your ability to write scalable and maintainable CSS for larger projects.

6. Final Round – Live Coding or Design Discussion

The final round may involve live coding or a discussion about your approach to relevant CSS challenges. Interviewers will evaluate how you solve problems on the fly, your design decisions, and how clearly you communicate your thought process.

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Now that you have a better understanding of the interview rounds, let’s check out some common CSS interview questions for beginner level.

Top CSS Interview Questions for Beginner Level 

Understanding the basics of CSS is crucial for any web developer, and having a solid grasp of fundamental concepts is important for acing beginner-level interviews. In this section, we’ll cover key CSS interview questions that will help you demonstrate your knowledge of styling and layout techniques. 

You’ll also learn how to apply these concepts to create effective and attractive websites. Preparing for these questions will help you showcase your foundational understanding of CSS and its role in web design.

1. What is CSS and how does it contribute to web design and development?

How to Answer: 

CSS stands for Cascading Style Sheets. In this question, you should begin by defining CSS and explain that it is a stylesheet language used to describe the presentation of a web document written in HTML or XML. Go beyond the definition and describe its role in web development, emphasizing how it controls layout, colors, fonts, and spacing. Discuss its importance in improving a website's design, accessibility, and responsiveness by keeping the content separate from the presentation. It’s also important to mention that CSS plays a crucial role in making websites more visually engaging and user-friendly.

Sample Answer:

CSS, which stands for Cascading Style Sheets, is a styling language used to control the presentation of HTML or XML elements. It allows web developers to design and format the layout of web pages by controlling aspects like colors, fonts, spacing, and positioning of elements. CSS separates content (HTML) from design, which makes the web pages easier to manage and enhances accessibility. It also plays a major role in creating responsive designs that adapt to various screen sizes.

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2. Explain the history and evolution of CSS, and how it has shaped modern web design?

How to Answer:

In this answer, start by mentioning the origins of CSS as part of an effort to improve web design. CSS was created by Håkon Wium Lie and Bert Bos in the 1990s to style web pages beyond the capabilities of HTML. It was a response to the limitations of HTML, which was initially focused on the structure of a webpage but lacked flexibility in presentation. CSS was officially introduced by the World Wide Web Consortium (W3C) in 1996, with the goal of allowing more powerful and flexible page designs.

Sample Answer:

CSS originated in the early 1990s as a solution to the limitations of HTML. While HTML was designed to structure content, it was not well-suited for styling elements effectively. Håkon Wium Lie and Bert Bos developed CSS as a means to control the presentation of web pages. The first CSS specification was introduced by the W3C in 1996. Since then, CSS has evolved into a key technology for web design, enabling designers to create visually appealing websites while separating content from design.

Also Read: HTML Vs XML: Difference Between HTML and XML[2025]

3. What are the different versions of CSS, and how have they evolved over time?

How to Answer:

This question is about the evolution of CSS. Discuss the different versions of CSS, focusing on how they have evolved to add more features and functionality. CSS1 was the first version, introducing basic styling capabilities, CSS2 introduced more advanced layout features, and CSS3 brought modularity, allowing for more flexibility with new features like animations, transitions, and flexbox. CSS4, though still being developed, aims to provide even more powerful tools for developers. Also, explain that each version builds upon the previous one to expand the scope and functionality of CSS.

Sample Answer:

CSS has evolved through several versions:

• CSS1: The first version, introduced in 1996, provided basic styling for text, colors, and layouts.
• CSS2: Released in 1998, CSS2 expanded CSS1 by adding positioning, media queries, and improved support for tables.
• CSS3: Introduced in the early 2000s, CSS3 is modular, breaking down the styling features into smaller modules for easier implementation. CSS3 brought major features like transitions, animations, flexbox, and media queries for responsive design.
• CSS4: Still in development, CSS4 aims to introduce even more advanced features, such as additional selectors and new layout techniques.

Also Read: CSS vs CSS3: Understand the Difference Between CSS and CSS3

4. What are the limitations of CSS, and how do they impact its usage in modern web development?

How to Answer:

While CSS is a powerful tool, it does have certain limitations. It is important to mention that CSS is purely a styling language and cannot handle dynamic behavior or logic-based changes, which JavaScript typically manages. Also, CSS does not support tasks like calculating values or manipulating content dynamically. In addition, CSS can sometimes face challenges in controlling certain layout elements across different browsers, leading to compatibility issues. It's also limited in complex behaviors, such as animations that require interaction, which requires the use of JavaScript.

Sample Answer:

CSS is primarily designed for styling, and while it is powerful, it has its limitations. For instance, CSS cannot perform dynamic content manipulation like JavaScript can. It cannot react to user interactions beyond simple hover states and pseudo-classes. CSS also cannot perform calculations or make complex logic-based decisions. Additionally, CSS cannot manipulate content directly, such as adding or removing HTML elements. There are also limitations in certain layout controls, such as vertical centering, which sometimes require workarounds.

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5. What are the key benefits of using CSS in web development, and how does it improve both design and performance?

How to Answer:

Discuss the primary advantages of CSS, including performance improvements, maintainability, and design flexibility. Emphasize that separating content from design allows for easier updates and greater consistency across large websites. Additionally, CSS improves page load times by reducing the amount of HTML code, as the design is handled separately. Talk about how CSS helps make websites more accessible by offering a clear separation between the content and its presentation. Lastly, mention that CSS enables responsive web design, which adapts the layout to different screen sizes.

Sample Answer:

CSS provides several key benefits:

• Performance: By separating content from styling, CSS reduces the amount of HTML code needed, leading to faster page loads.
• Maintainability: A single CSS file can control the styles for an entire website, making it easier to maintain and update the design.
• Consistency: With CSS, you can ensure uniform design across multiple pages, improving the overall user experience.
• Accessibility: By separating content from design, CSS improves accessibility and helps create layouts that are more readable and navigable.
• Responsive design: CSS allows you to create flexible layouts that adjust according to screen size, ensuring a seamless experience across different devices.

6. What are CSS frameworks, and how do they simplify the process of web design and development?

How to Answer:

CSS frameworks are pre-written libraries of CSS code that are designed to make the process of styling a website faster and easier. They include pre-defined grids, styles, and components, so developers don’t have to start from scratch every time they build a site. Mention popular frameworks like Bootstrap and Foundation, which are widely used in the industry. These frameworks also follow best practices and ensure that websites are built with consistency and accessibility in mind. Explain that frameworks reduce development time and help developers focus on the content and functionality of a website rather than the design.

Sample Answer:

CSS frameworks are libraries that contain pre-written CSS code for common layout and design components. They are designed to speed up development and ensure consistency across a website. Popular frameworks like Bootstrap, Foundation, and Bulma provide reusable styles for elements like grids, buttons, forms, and navigation bars. By using these frameworks, developers can build responsive and well-designed websites more quickly without having to write custom CSS from scratch.

Also Read: How to Install Bootstrap in Angular? Top 5 Ways

7. Who postulates the specifications of CSS?

How to Answer:

Clearly state that the specifications of CSS are maintained by the World Wide Web Consortium (W3C). Discuss the role of W3C in standardizing web technologies and how they ensure that CSS specifications are followed by all browsers, promoting consistency across the web.

Sample Answer:

The specifications of CSS are maintained by the World Wide Web Consortium (W3C), which is the governing body for web standards. W3C is responsible for ensuring that web technologies, including CSS, are consistent and compatible across all browsers. By developing these standards, W3C enables developers to create web pages that perform consistently, regardless of the browser or platform being used.

8. What are the ways in which CSS can be integrated into a website?

How to Answer:

Explain the three main methods of integrating CSS into a website: inline, embedded, and external. Provide examples for each and discuss when one method might be preferred over another. Inline styles are best for quick, one-off styling, embedded styles are used for styling a single page, and external is ideal for large sites where styles need to be reused.

Sample Answer:

CSS can be integrated into a website in three primary ways:

• Inline CSS: Styles are applied directly within an HTML element using the style attribute. This method is useful for quick changes but not ideal for multiple elements.
• Embedded CSS: CSS is written within the <style> tag in the HTML document's <head>. This method is useful when styling a single page.
• External CSS: The CSS is written in a separate .css file and linked to the HTML document using the <link> tag. This is the most efficient approach for large websites, as it allows styles to be reused across multiple pages.

Also Read: HTML Tutorial: The Complete Guide

9. What merits and disadvantages do External Style Sheets offer?

How to Answer:

Discuss the benefits of using external style sheets, such as improved website performance, easier maintenance, and consistency across multiple pages. Also, mention the downsides, such as the need for an additional HTTP request, which can affect page load time.

Sample Answer:

External style sheets offer several advantages:

• Centralized management: One file controls the styles for multiple pages, making it easy to maintain and update.
• Reusability: The same styles can be applied to many pages, ensuring consistency.
• Performance: Once loaded, the browser caches the external CSS file, reducing the load time for subsequent pages.

However, a potential disadvantage is that the browser needs to make an additional HTTP request to fetch the external file, which can slightly delay the page load time on the first visit.

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10. State the benefits and disadvantages of Embedded Style Sheets.

How to Answer:

Explain that embedded styles are useful for styling a single page and don’t require additional HTTP requests. However, they are not ideal for larger websites, as they cannot be reused across multiple pages and can lead to redundancy.

Sample Answer:

Embedded style sheets are placed within the <style> tag in the HTML document. The key benefit is that there is no additional HTTP request since the styles are embedded directly in the page. This is ideal for styling a single page with unique styles. However, the downside is that embedded styles cannot be reused across multiple pages, which makes them less efficient for large websites witha consistent design.

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11. What are the different CSS selectors?

How to Answer:

Discuss the different types of CSS selectors, including element selectors, class selectors, ID selectors, and attribute selectors. Also, mention more advanced selectors like pseudo-classes and pseudo-elements.

Sample Answer:

CSS selectors are used to target HTML elements for styling. The basic types include:

• Element selectors: Target HTML elements directly (e.g., h1, p).
• Class selectors: Target elements with a specific class (e.g., .button).
• ID selectors: Target elements with a unique ID (e.g., #header).
• Attribute selectors: Target elements based on their attributes (e.g., [type="text"]).

There are also pseudo-classes (:hover, :focus) and pseudo-elements (::before, ::after) that add more advanced targeting options.

12. What are :hover and :focus in CSS?

How to Answer:

Explain that :hover and :focus are pseudo-classes used to style elements when a user interacts with them. :hover is triggered when the user hovers over an element, and :focus is triggered when an element gains focus (e.g., via clicking or tabbing).

Sample Answer:

The :hover pseudo-class is used to style elements when the user hovers over them, typically used for buttons or links. For example, a:hover { color: red; } changes the link color when hovered. The :focus pseudo-class is used when an element gains focus, such as when a user clicks on a text input or uses the Tab key to navigate. For example, input:focus { border: 2px solid blue; } applies a border when the input field is focused.

13. What is the font-family property in CSS?

How to Answer:

Discuss the font-family property, which specifies the typeface of text in an element. Mention how it can take a list of fonts as fallbacks in case the preferred font is unavailable.

Sample Answer:

The font-family property in CSS specifies the font to be used for text within an element. It can list multiple fonts, separated by commas, to provide fallbacks in case the preferred font is unavailable. For example: will use Arial, but if that font isn't available, it will default to any available sans-serif font.

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14. What are the width and height properties in CSS?

How to Answer:

Explain that the width and height properties are used to control the size of an element. You can set these properties to specific values (e.g., pixels or percentages), and they can also be used with the max-width and max-height properties for responsive design.

Sample Answer:

The width and height properties are used to define the size of an element. For example, div { width: 200px; height: 100px; } will set the dimensions of a <div> element. You can also use percentage values to make elements responsive, such as width: 50%. Additionally, max-width and max-height limit the size of an element without causing overflow.

15. What are the different methods to apply colors in CSS, and how do they affect design and accessibility?

How to Answer:

Discuss how colors can be applied using various methods in CSS, including named colors, hexadecimal values, RGB, RGBA, HSL, and HSLA.

Sample Answer:

You can apply CSS colors using different formats:

• Named colors (e.g., color: red;)
• Hexadecimal (e.g., color: #ff0000;)
• RGB (e.g., color: rgb(255, 0, 0);)
• RGBA (e.g., color: rgba(255, 0, 0, 0.5);)
• HSL (e.g., color: hsl(0, 100%, 50%);)
• HSLA (e.g., color: hsla(0, 100%, 50%, 0.5);)

Each method offers flexibility in defining colors, with RGBA and HSLA allowing for opacity control.

16. What is the difference between class and id in CSS?

How to Answer:

Explain that class selectors are reusable, while id selectors are unique. Emphasize that id has a higher specificity than class and is used for targeting a single element, whereas class can be used for multiple elements.

Sample Answer:

class selectors are reusable and can be applied to multiple elements on a page, making them ideal for styling groups of elements. For example, .button { color: red; } applies to all elements with the button class. id selectors, on the other hand, are unique and can only be applied to one element per page. For example, #header { font-size: 24px; } targets an element with the id="header". The id selector has a higher specificity than the class selector.

17. What are em and rem units in CSS?

How to Answer:

Discuss the difference between em and rem. em is relative to the parent element's font size, while rem is relative to the root element's font size (typically the <html> element).

Sample Answer:

em is a relative unit that refers to the font size of the parent element. For example, if the parent element has a font size of 16px, 1em will equal 16px. rem (root em) is also relative, but it is based on the font size of the root element (<html>), which is usually set to 16px by default. For instance, 1rem will always be 16px regardless of the font size of its parent.

18. What is the difference between inline, block, and inline-block?

How to Answer:

Explain how inline, block, and inline-block elements differ in their behavior regarding layout and positioning. Block elements take up the full width, inline elements flow within text, and inline-block elements can have width and height but don’t break the line.

Sample Answer:

inline elements do not start on a new line and only take up as much width as necessary. Examples include <span> and <a>.

block elements, such as <div>, take up the full width of their container and start on a new line.

inline-block elements are similar to inline elements in that they do not start on a new line, but they behave like block elements in that you can set their width and height.

19. What is the box-sizing property?

How to Answer:

Explain that the box-sizing property defines how the width and height of an element are calculated. The default value is content-box, but border-box includes padding and border in the element's total width and height.

Sample Answer:

The box-sizing property defines how the total width and height of an element are calculated. The default value is content-box, where only the content is considered for width and height, and padding/border is added outside. With box-sizing: border-box, the width and height include padding and border, making it easier to manage layouts and avoid unexpected size increases.

Also Read: Top 15 CSS Project Ideas for Beginners to Boost Your Resume in 2025

20. What is the float property in CSS?

How to Answer:

Discuss the float property, which was originally used to wrap text around elements like images. Explain that while it is now less commonly used for layout due to newer techniques like Flexbox and Grid, it can still be useful in specific cases.

Sample Answer:

The float property allows elements to be pushed to the left or right, with text and other inline elements flowing around them. It was originally used for image layouts, such as wrapping text around images. However, with the advent of Flexbox and Grid, float is now less commonly used for layout, as these newer properties offer more control and flexibility.

21. What are pseudo-classes in CSS?

How to Answer:

Explain pseudo-classes in CSS, which target an element in a specific state or condition. Common examples include :hover, :focus, and :nth-child.

Sample Answer:

Pseudo-classes in CSS allow you to target elements based on their state or position within a document. For example, :hover applies styles when the user hovers over an element, :focus applies when an element is focused (like a form field), and :nth-child(n) targets elements based on their position within their parent.

22. What is the visibility property in CSS?

How to Answer:

Explain that the visibility property controls whether an element is visible or not. It differs from display: none in that it keeps the element's space in the layout even when it is hidden.

Sample Answer:

The visibility property in CSS controls whether an element is visible or hidden. Unlike display: none, which removes the element from the layout entirely, visibility: hidden hides the element but still occupies space in the layout. This can be useful when you want to hide elements without affecting the layout.

23. How do you make a website mobile-friendly using CSS?

How to Answer:

Discuss the importance of using responsive design principles, including media queries, flexible layouts (using Flexbox or Grid), and ensuring text is legible without zooming. Mention using percentage-based widths for flexibility across different screen sizes.

Sample Answer:

To make a website mobile-friendly, you should use responsive design techniques, primarily through the use of media queries. Media queries allow you to apply different styles depending on the screen size, ensuring your layout adapts to various devices. Additionally, using flexible layouts with flex or grid, and setting font sizes and widths with relative units like percentages or rem, ensures the website looks good on all screen sizes.

24. What is the opacity property in CSS?

How to Answer:

Discuss how the opacity property controls the transparency level of an element. Values range from 0 (fully transparent) to 1 (fully opaque), and you can use it for effects like fading.

Sample Answer:

The opacity in CSS controls the transparency of an element. The value can range from 0 (completely transparent) to 1 (completely opaque). For example, opacity: 0.5 will make an element 50% transparent. It’s commonly used for visual effects, such as creating hover or fade-in/out transitions.

25. What is the @keyframes rule in CSS?

How to Answer:

Explain how the @keyframes rule allows you to define animations in CSS. It lets you specify how an element should change at different points in the animation sequence.

Sample Answer:

@keyframes defines the intermediate steps of an animation. For example, you can create an animation that moves an element from left to right by defining the from and to states or multiple keyframes for more complex animations. For instance:

@keyframes slide { from { left: 0; } to { left: 100px; } }.

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If you’re interviewing at the intermediate level, here are some CSS interview questions that go a bit deeper than the beginner level. 

Top CSS Interview Questions for Intermediate Level 

Prepare for the intermediate-level CSS interview questions by strengthening your understanding of more advanced concepts. In this section, we’ll cover essential topics such as Flexbox, Grid, CSS positioning, pseudo-classes, and media queries. 

These questions test your ability to apply CSS in complex design scenarios, optimize layouts for responsiveness, and create scalable, maintainable stylesheets. Mastering these concepts will help you demonstrate your practical skills and problem-solving abilities during the interview.

26. What is a contextual selector in CSS? Provide an example.

How to Answer:

Contextual selectors are used to select elements that are in a specific context relative to other elements. This can be a parent-child or sibling relationship between elements. You should explain how a contextual selector targets an element based on its position relative to another.

Sample Answer:

A contextual selector is a selector that applies styles to an element based on its relationship to other elements. For example, a selector like div p will apply styles to all <p> elements inside a <div>. Contextual selectors allow for more precise targeting without requiring additional classes or IDs.

27. What are the benefits of using the :nth-child() pseudo-class?

How to Answer:

Explain how the :nth-child() pseudo-class can be used to select elements based on their position within a parent element. It can be used for applying styles to specific elements such as every odd or even element, or to every 3rd, 4th, etc.

Sample Answer:

:nth-child() is a powerful pseudo-class that allows you to select elements based on their position in a parent container. For example, li:nth-child(odd) targets every odd <li> element in a list, while li:nth-child(2n) targets every second <li>. This helps to avoid unnecessary classes and allows for more efficient and flexible styling.

28. How does the display property work in CSS?

How to Answer:

Discuss the different values for the display property, such as block, inline, inline-block, and none, and how each affects the behavior of an element in terms of layout.

Sample Answer:

The display property defines how elements are displayed on a webpage.

• Block elements take up the full width and start on a new line.
• Inline elements take up only the space necessary for their content and do not start on a new line.
• Inline-block combines the behavior of both block and inline elements.
• None hides the element from the layout.

The display property is essential for managing layouts and positioning elements effectively.

29. What is Flexbox, and how does it help in layout design?

How to Answer:

Describe Flexbox as a layout model in CSS that provides an easy and efficient way to lay out elements in one dimension (either as rows or columns). Explain how Flexbox helps align elements horizontally and vertically.

Sample Answer:

Flexbox is a CSS layout module designed to simplify the process of aligning and distributing space among items within a container. By setting the container’s display property to flex, you can control the direction of the layout (either row or column), and adjust spacing, alignment, and order of items without using floats or positioning. Flexbox makes building complex layouts much simpler and more flexible.

Also Read: Bootstrap vs Material UI: An In-depth Comparison [2025]

30. What is the difference between visibility: hidden and display: none?

How to Answer:

Explain that visibility: hidden hides an element but still occupies space in the layout, while display: none removes the element from the document flow entirely, causing the layout to adjust.

Sample Answer:

visibility: hidden hides an element, but it still occupies space in the layout, so the layout of other elements remains unaffected. In contrast, display: none removes the element from the layout entirely, and the space it occupied is reclaimed, causing the surrounding elements to shift. Use visibility: hidden when you want to hide content but maintain its space, and display: none when you want to remove the element completely.

31. Explain the position property and its values in CSS.

How to Answer:

The position property in CSS is used to control the positioning of an element. Describe the different values it can take, such as static, relative, absolute, fixed, and sticky, and explain the use cases for each.

Sample Answer:

The position property defines how an element is positioned on the page.

• Static: The default positioning; elements are positioned according to the normal document flow.
• Relative: The element is positioned relative to its normal position, allowing for slight adjustments with top, right, bottom, and left.
• Absolute: The element is positioned relative to its nearest positioned ancestor.
• Fixed: The element is positioned relative to the viewport, remaining in the same place even when the page is scrolled.
• Sticky: The element toggles between relative and fixed based on the scroll position.

32. What is the z-index in CSS, and how does it work?

How to Answer:

Describe the z-index property, which controls the stacking order of elements along the z-axis (the depth of the layout). Explain how elements with a higher z-index value are stacked in front of elements with a lower value.

Sample Answer:

z-index is a CSS property that controls the stacking order of elements that overlap. It only works on positioned elements (those with position: relative, absolute, fixed, or sticky). Elements with a higher z-index value are stacked in front of those with a lower value. The default z-index is 0, but you can assign higher or lower values to control the layering of elements.

33. Explain the difference between padding and margin in CSS.

How to Answer:

Discuss the difference between padding (the space between an element's content and its border) and margin (the space outside an element's border). Explain that padding is part of the element’s box model, whereas margin separates the element from other elements.

Sample Answer:

Padding is the space between an element's content and its border. It helps create space inside the element, surrounding its content. Margin, on the other hand, is the space outside the element’s border, creating a gap between the element and other elements on the page. Padding adds to the total size of the element, while margin does not.

34. What is a flex container in Flexbox?

How to Answer:

Explain that the flex container is the parent element that uses Flexbox to lay out its child items. It must have display: flex or display: inline-flex to activate Flexbox properties.

Sample Answer:

A flex container is an element that is defined using display: flex or display: inline-flex. This activates Flexbox layout, allowing for more efficient alignment and distribution of space among its child elements. The flex container provides control over the direction, spacing, and alignment of the flex items inside it.

Also Read: Top 30 Interview Question & Answers for Freshers

35. What is the difference between inline and block elements in CSS?

How to Answer:

Discuss how inline elements flow within text and only take up as much space as necessary, whereas block elements take up the entire width of their container and start on a new line.

Sample Answer:

inline elements, like <span>, flow along with the surrounding text and only take up as much width as needed. They don’t break the flow of the document. In contrast, block elements, such as <div> and <p>, take up the full width of their parent container and start on a new line, stacking vertically.

36. How do you center an element using Flexbox?

How to Answer:

Explain how Flexbox makes it easy to center items both horizontally and vertically with properties like justify-content and align-items. Mention the align-self property for individual alignment.

Sample Answer:

To center an element using Flexbox, you need to set the flex container’s display to flex. Then, use justify-content: center to center items horizontally and align-items: center to center them vertically. You can also use align-self on individual items to control their vertical alignment independently.

37. What is the use of box-sizing property in CSS?

How to Answer:

Describe the box-sizing property, which controls how the total width and height of an element are calculated, including padding and borders.

Sample Answer:

box-sizing is a property that defines how the width and height of an element are calculated. By default, the width and height properties only apply to the content area. However, when set to box-sizing: border-box, the padding and border are included in the element’s total width and height, which makes it easier to manage layouts.

38. Explain the @media rule in CSS.

How to Answer:

The @media rule in CSS allows you to apply styles based on certain conditions, like screen width, height, orientation, etc. Explain how media queries help create responsive designs.

Sample Answer:

@media is a rule in CSS that allows you to apply different styles depending on the characteristics of the device or viewport. For example, you can use @media to adjust the layout for mobile devices using @media (max-width: 600px). Media queries are essential for creating responsive websites that adapt to different screen sizes.

Also Read: How To Answer Why Should You Be Hired Interview Question

39. What are pseudo-elements in CSS?

How to Answer:

Describe how pseudo-elements allow you to add special styles to parts of an element without modifying the HTML. Common examples include ::before and ::after.

Sample Answer:

Pseudo-elements in CSS, such as ::before and ::after, allow you to style parts of an element that don’t exist in the HTML markup. For example, ::before can be used to insert content before an element, and ::after can be used to insert content after it, without the need for additional HTML elements.

40. What is the difference between inline-block and block?

How to Answer:

Explain that inline-block behaves like an inline element but allows for setting width and height, unlike regular inline elements. It also behaves differently in terms of layout compared to block elements.

Sample Answer:

inline-block elements are similar to inline elements, meaning they do not start on a new line, but they also behave like block elements in that you can set their width and height. In contrast, block elements take up the full width of their container and start on a new line.

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41. What is the purpose of the @import rule in CSS?

How to Answer:

The @import rule in CSS allows you to include an external stylesheet within your current stylesheet. Explain its syntax and how it functions, but also mention that using @import can increase page load time due to additional HTTP requests.

Sample Answer:

@import is used to import an external CSS file into your current stylesheet. For example, @import url('styles.css'); allows you to link to an external stylesheet from within your main CSS file. However, it's generally better to use the <link> tag in the HTML for linking stylesheets, as @import can result in additional HTTP requests and may slow down page loading.

42. What is the difference between absolute, relative, and fixed positioning in CSS?

How to Answer:

Discuss how each positioning type works and when to use them. absolute positions an element relative to its nearest positioned ancestor, relative positions an element relative to its original position, and fixed positions the element relative to the viewport.

Sample Answer:

absolute positioning places an element relative to its closest positioned ancestor (an element with position: relative, absolute, or fixed).

relative positioning moves an element relative to its original position in the document flow.

fixed positioning fixes an element relative to the viewport, meaning it stays in place even when scrolling. Use absolute for precise placement within a container, relative for slight adjustments, and fixed for elements that need to stay visible, like a sticky navigation bar.

43. What are media queries, and how are they used in responsive design?

How to Answer:

Explain that media queries are a way to apply different CSS rules based on conditions like screen width, resolution, or device type. Media queries are essential for building responsive websites that adapt to various screen sizes.

Sample Answer:

Media queries in CSS allow you to apply different styles depending on the characteristics of the device or viewport. For example, @media (max-width: 600px) targets devices with a screen width of 600px or smaller. Media queries are essential for creating responsive designs, ensuring a website looks good on all devices, from desktop to mobile.

44. What is the purpose of the flexbox layout model in CSS?

How to Answer:

Describe Flexbox as a layout model for one-dimensional layouts, where you can align and distribute space among items in a container. Explain its flexibility, such as its ability to align items in rows or columns, and its efficiency in creating responsive layouts.

Sample Answer:

Flexbox is a layout model in CSS designed for creating one-dimensional layouts. It makes it easy to align and distribute space among items within a container. Flexbox is particularly useful for creating responsive designs as it allows items to adjust and resize depending on the available space, either in rows or columns.

45. What is the difference between position: absolute and position: fixed?

How to Answer:

Clarify the distinction between absolute and fixed positioning. absolute positions an element relative to its closest positioned ancestor, while fixed positions the element relative to the viewport and remains in place even during scrolling.

Sample Answer:

position: absolute positions an element relative to the nearest positioned ancestor (an element with position: relative, absolute, or fixed).

position: fixed positions an element relative to the viewport, meaning it stays in place even when the page is scrolled. fixed is often used for sticky elements like navigation bars that need to stay visible while scrolling.

46. How does the box-sizing property affect element sizing?

How to Answer:

Describe box-sizing in CSS and how it changes how the width and height of an element are calculated. Explain the default content-box value and the more commonly used border-box value, which includes padding and borders in the element’s total width and height.

Sample Answer:

The box-sizing property controls how the width and height of an element are calculated. By default, with box-sizing: content-box, the width and height only include the content area, and padding/borders are added outside this area. With box-sizing: border-box, the width and height include the padding and border, making it easier to manage layouts without worrying about overflow caused by extra padding.

47. What is the z-index in CSS, and how does it work?

How to Answer:

Explain the z-index property and its role in controlling the stacking order of overlapping elements. It works with positioned elements, and elements with a higher z-index will be stacked above those with a lower value.

Sample Answer:

z-index is a CSS property that controls the stacking order of overlapping elements. The higher the z-index, the closer the element is to the front. It works only on positioned elements (those with position: relative, absolute, fixed, or sticky). For example, div { z-index: 2; } will place the element above others with a lower z-index value.

48. What are pseudo-classes in CSS, and how do they work?

How to Answer:

Describe pseudo-classes as special keywords in CSS used to target elements based on their state or position. Examples include :hover, :focus, and :nth-child().

Sample Answer:

Pseudo-classes are used to target elements based on their state or position. For example, :hover applies styles when the user hovers over an element, :focus targets elements that have focus (like input fields), and :nth-child() selects elements based on their position in a list. These allow for more dynamic and interactive styling without needing JavaScript.

49. What is the difference between display: none and visibility: hidden?

How to Answer:

Explain that display: none removes an element from the document flow entirely, while visibility: hidden hides an element but still takes up space in the layout.

Sample Answer:

display: none removes an element from the document flow entirely, meaning it does not occupy any space in the layout. On the other hand, visibility: hidden hides an element but still keeps its space reserved, meaning other elements around it will not shift or adjust in response.

50. What are @keyframes used for in CSS?

How to Answer:

Explain that @keyframes define animations in CSS by specifying the starting and ending states of an element and the intermediate steps. They help create smooth transitions between different states.

Sample Answer:

@keyframes is used to define CSS animations by specifying the intermediate steps between the starting and ending states of an element. For example, @keyframes move { 0% { left: 0; } 100% { left: 100px; } } defines a movement animation where the element moves from left: 0 to left: 100px.

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If you’re an expert interviewing for a senior position, here are some common CSS interview questions at an expert level. 

Top CSS Interview Questions for Expert Level 

At the expert level, CSS interview questions focus on your deep understanding of advanced techniques and your ability to solve complex design challenges. 

In this section, we’ll cover topics like CSS Grid, custom properties (CSS variables), animations, and performance optimization. These questions evaluate your ability to create high-performance, scalable, and visually appealing web applications.

51. Explain the concept of float in CSS.

How to Answer:

Discuss how float was originally used to position elements like images in text, and how it affects the flow of surrounding elements. Explain its limitations and modern alternatives.

Sample Answer:

The float property is used to push an element to the left or right, allowing content to flow around it. It was commonly used for creating layouts with sidebars or positioning images. However, float has limitations and can cause layout issues, which is why Flexbox and Grid have become more popular alternatives.

52. What are CSS variables?

How to Answer:

Describe how CSS variables enable you to store and reuse values throughout a stylesheet. Mention their flexibility, such as dynamic changes at runtime with JavaScript.

Sample Answer:

CSS variables, also known as custom properties, allow you to store values in a variable-like structure. These variables are defined with the -- prefix and can be reused throughout your stylesheet. For example, --primary-color: blue;. CSS variables make your code more maintainable and can even be dynamically updated with JavaScript.

53. What is the transition property in CSS?

How to Answer:

Explain the transition property as a way to create smooth animations when certain properties change. Mention common use cases such as hover effects or smooth changes in layout.

Sample Answer:

The transition property allows you to create smooth animations when properties of an element change. For example, you can use transition: all 0.3s ease; to make an element's color change smoothly when hovered over. Transitions are commonly used to add visual interactivity to elements without requiring JavaScript.

Also Read: 10 Practical Applications of JavaScript And Career Tips

54. What is the purpose of z-index?

How to Answer:

Discuss the role of the z-index property in stacking elements, which determines the order of overlapping items. Mention its dependency on positioning.

Sample Answer:

z-index controls the stacking order of elements along the z-axis. It only works on positioned elements (position: relative, absolute, fixed, sticky). Elements with a higher z-index value will appear on top of elements with a lower value, allowing developers to layer elements on a webpage.

55. Explain the difference between rem and em units.

How to Answer:

Describe the difference between rem and em units in terms of their reference points. rem is relative to the root element, while em is relative to the parent element.

Sample Answer:

rem stands for 'root em' and is relative to the font size of the root element (<html>), making it easier to maintain consistent sizing across a website. em, on the other hand, is relative to the font size of the parent element, which can cause nested elements to scale unexpectedly if not carefully managed.

56. What are CSS grid and how does it differ from Flexbox?

How to Answer:

Describe CSS Grid as a two-dimensional layout system, compared to Flexbox's one-dimensional system. Explain when to use each and how Grid is better suited for complex layouts.

Sample Answer:

CSS Grid is a two-dimensional layout system that allows for the design of both rows and columns, making it ideal for complex page layouts. Flexbox, in contrast, is one-dimensional, working along either a row or column. Grid is best suited for multi-row and column layouts, while Flexbox is simpler for linear layouts.

57. What is object-fit in CSS?

How to Answer:

The object-fit property in CSS is used to specify how an image or video should fit within its container. Mention different values such as cover, contain, and fill.

Sample Answer:

object-fit defines how an image or video should be resized to fit its container.

• cover: Scales the content to fill the container while maintaining aspect ratio, cropping if necessary.
• contain: Scales the content to fit within the container without cropping, maintaining aspect ratio.
• fill: Stretches the content to fill the container, ignoring the aspect ratio.

Also Read: 12 Best UI UX Designer Tools: Choosing the Right Software for Your Projects

58. Explain @import in CSS.

How to Answer:

The @import rule allows you to import an external stylesheet into your current stylesheet. Discuss its usage and the fact that it can increase page load times due to additional HTTP requests.

Sample Answer:

@import is used to import an external CSS file into another CSS file. For example, @import url('styles.css'); allows you to bring in styles from another file. While this can help organize your styles, it can negatively impact performance by adding additional HTTP requests. It’s generally better to use <link> tags for external stylesheets in HTML.

59. What is box-sizing: border-box?

How to Answer:

The box-sizing property controls how the total width and height of elements are calculated. Explain that border-box includes padding and borders in the element's total size, unlike the default content-box.

Sample Answer:

box-sizing: border-box includes padding and borders within the total width and height of an element, making it easier to calculate and manage element sizes. This is often preferred in modern web design because it allows you to set precise dimensions without worrying about padding and borders expanding the element beyond its set size.

60. What is the @media rule in CSS?

How to Answer:

The @media rule is used in CSS to apply different styles depending on the device characteristics, such as screen size or orientation. Explain its role in making websites responsive.

Sample Answer:

@media is used to apply styles based on device-specific conditions like screen width, resolution, or orientation. For example, @media (max-width: 600px) can be used to change the layout of a website for mobile devices. Media queries allow developers to create responsive designs that adjust to various screen sizes.

61. What is CSS Grid, and when would you use it over Flexbox?

How to Answer:

Explain that CSS Grid is a two-dimensional layout system that allows you to work with both rows and columns, whereas Flexbox is one-dimensional and works in either rows or columns. Discuss how CSS Grid is ideal for complex layouts with multiple sections, while Flexbox works well for simpler, linear layouts.

Sample Answer:

CSS Grid is a two-dimensional layout system that enables designers to work with both rows and columns simultaneously. It is ideal for complex layouts with multiple rows and columns, like a magazine layout or a dashboard. Flexbox is better for simpler, one-dimensional layouts, such as navigation bars or aligning items in a row or column. CSS Grid provides more control over the positioning of elements, while Flexbox is more flexible and easy to use for basic layouts.

62. How does the will-change property improve performance in CSS?

How to Answer:

Discuss that will-change helps the browser optimize an element's rendering by indicating which properties are likely to change. This can improve performance by letting the browser prepare for changes in advance.

Sample Answer:

The will-change property is used to inform the browser about properties of an element that are likely to change. This allows the browser to optimize rendering and avoid unnecessary recalculations. For example, using will-change: transform; on an element indicates that the transform property will be animated, so the browser can optimize the performance. However, overuse of this property can lead to performance issues, so it should be used sparingly.

63. What is the purpose of the ::after pseudo-element in CSS?

How to Answer:

Explain that ::after is used to insert content after an element without modifying the HTML. It is commonly used for adding decorative content or clearing floated elements.

Sample Answer:

The ::after pseudo-element is used to insert content after an element. This content is not part of the HTML markup, but it can be used for decorative purposes, such as adding icons, or for clearing floated elements. For example, div::after { content: ''; display: block; clear: both; } is often used to clear floats inside a container.

64. What is the difference between rem and em units, and when would you use one over the other?

How to Answer:

Clarify that both rem and em are relative units, but rem is always relative to the root font size, while em is relative to the font size of the parent element. rem is typically used for consistent sizing, while em is better for contextual scaling.

Sample Answer:

rem stands for 'root em' and is relative to the font size of the root element (<html>), usually 16px by default. It's useful when you want consistent, predictable sizing across the entire site. On the other hand, em is relative to the font size of its closest parent element, so it can cascade and compound based on nested elements. rem is great for global consistency, while em is useful for elements that need to scale based on their context.

65. What is the ::before pseudo-element, and how does it differ from ::after?

How to Answer:

Describe the ::before pseudo-element as used to insert content before an element, while ::after inserts content after an element. Both pseudo-elements are useful for adding content to elements without modifying the HTML.

Sample Answer:

The ::before pseudo-element is used to insert content before an element’s actual content, while ::after inserts content after the element. Both pseudo-elements are typically used to add visual decorations or effects without altering the HTML structure. For example, h1::before { content: '→ '; } would add an arrow before the heading text.

Also Read: 55 Computer Science Interview Questions And Answers [For Freshers & Experienced]

66. How do CSS variables (custom properties) work, and what are their benefits?

How to Answer:

Explain that CSS variables allow you to store values in custom properties, making it easier to manage and reuse values like colors, sizes, and fonts. You can dynamically update these variables via JavaScript, enhancing flexibility.

Sample Answer:

CSS variables (custom properties) enable you to store values in properties prefixed with -- (e.g., --primary-color: blue;). These variables can be reused throughout your CSS, making your stylesheets easier to maintain. They also allow you to dynamically update values via JavaScript, which is useful for creating themes or making global design changes across a website.

67. What is the clamp() function in CSS?

How to Answer:

Describe clamp() as a CSS function that allows you to set a value that adjusts dynamically within a defined range. It takes three parameters: a minimum value, a preferred value, and a maximum value.

Sample Answer:

The clamp() function in CSS is used to set a value that adjusts dynamically within a specified range. It takes three arguments: a minimum value, a preferred value, and a maximum value. For example, font-size: clamp(14px, 4vw, 24px); will set the font size to 14px at the smallest viewport size, scale it to 4% of the viewport width as the preferred value, and cap it at 24px at larger sizes.

68. Explain how CSS Grid works with nested grids.

How to Answer:

Explain that CSS Grid allows you to create grids inside grids by defining a grid on a parent container, and then applying a grid layout again on the child elements. This allows for complex, nested layouts.

Sample Answer:

CSS Grid enables the creation of nested grids, which allows you to create complex layouts. You can define a grid on a parent container and then apply grid properties to child elements. Each child grid can have its own rows and columns, allowing for flexible, nested layouts. For example, you might use a grid for the main layout and then use a grid inside a section for a more detailed layout.

69. What is the filter property in CSS, and how does it work?

How to Answer:

The filter property in CSS allows you to apply graphical effects like blur, brightness, contrast, grayscale, and more to an element. It’s often used for images and backgrounds, but can be applied to other elements as well.

Sample Answer:

The filter property in CSS is used to apply graphical effects such as blur, brightness, contrast, grayscale, and more to an element. For example, filter: blur(5px); applies a 5-pixel blur effect to an image. It’s commonly used for image manipulation, but can also be applied to text and other elements for visual effects.

70. What is the object-position property in CSS, and how does it work?

How to Answer:

Explain that object-position is used to control the position of media content (like images or videos) within its container. It is often used with object-fit to control how the content is displayed.

Sample Answer:

The object-position property specifies the position of an element's content, such as an image or video, within its container. It works in conjunction with the object-fit property to control how the content is resized and positioned. For example, object-position: center; centers the content within its container.

71. What are CSS transitions, and how do they work?

How to Answer:

Discuss how CSS transitions allow elements to change from one state to another smoothly over a specified duration. Mention common properties such as transition-property, transition-duration, and transition-timing-function.

Sample Answer:

CSS transitions allow you to smoothly animate changes in an element’s properties over a specified duration. For example, transition: background-color 0.3s ease; will animate the background color change over 0.3 seconds. You can control which property is animated, the duration of the animation, and the timing function to specify how the transition progresses.

72. How do you use the calc() function in CSS?

How to Answer:

Describe how the calc() function in CSS allows you to perform calculations to set property values, such as widths or margins. This is useful for combining units like percentages and pixels in one property.

Sample Answer:

calc() is a CSS function that allows you to perform calculations to determine property values. For example, width: calc(100% - 50px); will set the width of an element to 100% of its container minus 50px. This function can combine different units, such as percentages, pixels, and ems, making it useful for responsive designs.

73. What are media feature queries in CSS, and how do they enable responsive design?

How to Answer:

Explain how media features in CSS allow you to target specific device properties, such as screen width, height, or resolution, making it easier to apply styles based on device characteristics.

Sample Answer:

Media features are used within media queries to apply styles based on specific device characteristics, such as screen width, height, resolution, and orientation. For example, @media (min-width: 768px) applies styles only when the screen width is greater than or equal to 768px. Media features allow for more targeted and efficient responsive design.

74. What are the different values of the position property in CSS?

How to Answer:

Discuss the different positioning values in CSS, such as static, relative, absolute, fixed, and sticky. Provide examples of how each positioning type affects the layout.

Sample Answer:

position defines how an element is positioned within its container.

• static: The default value, where elements follow the normal document flow.
• relative: Positioned relative to its original position.
• absolute: Positioned relative to its closest positioned ancestor.
• fixed: Positioned relative to the viewport, staying in the same place when scrolling.
• sticky: Behaves like relative until a certain scroll point, then becomes fixed.

75. What is the purpose of the @supports rule in CSS?

How to Answer:

Explain that the @supports rule is used to apply styles only if the browser supports certain CSS features. This allows for feature queries and helps with progressive enhancement.

Sample Answer:

@supports is a rule in CSS that lets you apply styles only if the browser supports specific CSS properties or features. For example, @supports (display: grid) { ... } will only apply the styles inside the block if the browser supports CSS Grid. This allows developers to create fallback styles for older browsers and take advantage of new features in modern browsers.

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Prepare & Excel in Your CSS Interview with upGrad!

Having a strong understanding of CSS is key to excelling in web development interviews. With both foundational and advanced knowledge, you'll be prepared to handle various design and layout challenges. 

However, many developers find it challenging to stay current with the constantly evolving field. If you're looking to sharpen your CSS skills and gain practical experience, upGrad's software development courses offer the ideal solution. Learn from industry experts, build hands-on skills, and advance your career. 

Here are some of the top upGrad courses to help you advance in your Java development journey:

• Object Oriented Analysis and Design for Beginners
• Node.js For Beginners
• Learn Basic Python Programming
• Data Structures & Algorithms

For personalized guidance on advancing your CSS skills, reach out to upGrad’s counselors or visit your nearby upGrad career center. With expert support and a curriculum designed for real-world applications, you'll be well-prepared to tackle CSS interview questions at every level with confidence and precision.

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Reference: 
https://www.lambdatest.com/blog/best-css-trends/