CSS Interview Questions and Answers: Top 50 [Updated for 2025]

Q: What are the most commonly asked CSS interview questions for freshers?

Freshers are typically asked about CSS basics like selectors, box model, positioning techniques, and media queries. Employers look for candidates who can explain syntax and demonstrate how to use different CSS properties effectively.

Q: How do I prepare for advanced CSS interview questions?

To prepare for advanced CSS interview questions, focus on topics like CSS specificity, flexbox, grid layouts, responsive design strategies, animations, and CSS performance optimisation. Practice with real-world layout challenges and coding tasks.

Q: Do companies ask coding-based CSS scenario questions?

Yes, many interviewers test your ability to solve real-world layout problems using CSS. Scenario-based questions may involve centering elements, fixing layout breakages, managing text overflow, or implementing sticky headers.

Q: What’s the difference between inline, internal, and external CSS?

Inline CSS is written inside HTML tags using the style attribute. Internal CSS is placed within the HTML document's head section using a style block. External CSS resides in a separate .css file and is linked to the HTML. External CSS is preferred for better performance and scalability.

Q: Are CSS interview questions different for experienced professionals?

Yes. For experienced candidates, CSS interview questions often focus on performance tuning, CSS architecture methodologies, complex layout designs using Grid and Flexbox, advanced animations, and scalable stylesheet management techniques.

Preparing for a front-end developer or web designer interview in Singapore? Employers like Grab, Shopee, DBS Bank, Singtel, and GovTech often include CSS interview questions to assess your practical coding and layout skills. Whether you’re applying for a UI engineer role, a web development position, or a digital product team, a strong grasp of CSS fundamentals and advanced techniques is essential.

This article compiles the top 50 CSS interview questions and answers asked by recruiters and hiring managers in Singapore’s tech industry. The questions cover everything from selectors and layout techniques to responsive design, animations, and CSS performance optimisation.

If you’re targeting companies in e-commerce, fintech, government tech agencies, or digital consulting firms, this resource will help you prepare effectively for your next CSS interview in 2025.

🔽 Table of Contents

Basic CSS Interview Questions for Freshers
CSS Selectors and Positioning Interview Questions
CSS Flexbox and Grid Interview Questions
CSS Media Queries and Responsive Design Questions
CSS Animation and Transitions Interview Questions
Advanced CSS Interview Questions for Experienced
CSS Scenario-Based Interview Questions
CSS Performance and Best Practices Questions
FAQs on CSS Interview Preparation

Basic CSS Interview Questions for Freshers

1. What is CSS and why is it used in web development?

Sample Answer: CSS stands for Cascading Style Sheets. It is a style sheet language used to describe the presentation and layout of HTML elements on web pages. CSS controls visual aspects like colors, fonts, spacing, margins, borders, and positioning.

Without CSS, websites would appear as plain HTML without design or structure. CSS allows developers to create responsive designs, improve user experience, and maintain consistent styling across multiple web pages by applying styles globally.

2. What are the different types of CSS?

Sample Answer: CSS can be applied in three different ways in a web project:

Inline CSS: Styles are applied directly inside an HTML element using the style attribute.
Internal CSS: Styles are written within a <style> tag inside the HTML document’s <head> section.
External CSS: Styles are stored in a separate .css file and linked using the <link> tag. This is the most scalable and maintainable approach for large projects.

<link rel="stylesheet" href="styles.css">

3. What is the difference between Class and ID selectors in CSS?

Sample Answer: Both class and ID selectors are used to target HTML elements for styling, but they serve different purposes:

Class Selector (.): Used for styling multiple elements. Classes are reusable across the page.
ID Selector (#): Used for styling a single, unique element on the page.

In terms of CSS specificity, ID selectors have higher priority over class selectors.

.button  

#submitBtn

4. What is the Box Model in CSS?

Sample Answer: The CSS Box Model explains how each HTML element is rendered on the web page. It defines how elements occupy space and how padding, borders, and margins affect their total size.

The Box Model consists of four parts:

Content: The actual text or image inside the element.
Padding: Space between the content and the border.
Border: The line surrounding the padding and content.
Margin: Space between the element and its neighbouring elements.

div

5. What is the difference between Relative and Absolute positioning in CSS?

Sample Answer: Both relative and absolute are CSS position values but they behave differently:

Relative Positioning: Positions the element relative to its original place in the document flow.
Absolute Positioning: Positions the element relative to its nearest positioned ancestor (an ancestor with position relative, absolute, or fixed). If no such ancestor exists, it uses the viewport as reference.

div.relative  

div.absolute

6. How can you apply the same style to multiple elements in CSS?

Sample Answer: You can target multiple elements using a comma-separated list of selectors. This technique is useful for applying common styles to several HTML elements like headings, paragraphs, or buttons.

h1, h2, h3

This ensures consistency across different elements without repeating CSS code.

7. What are Pseudo-classes in CSS?

Sample Answer: Pseudo-classes allow you to define a special state of an element. They target elements based on user interaction, position in the DOM, or state (like :hover, :first-child, etc.).

Some common pseudo-classes include:

:hover – When a user hovers over an element.
:first-child – Selects the first child of a parent.
:focus – When an element receives focus, like an input field.

a:hover

CSS Selectors and Positioning Interview Questions

8. What are the different types of CSS selectors?

Sample Answer: CSS selectors are patterns used to target and style HTML elements. Different types of selectors help developers apply styles based on element names, classes, IDs, attributes, states, and relationships.

Main types of CSS selectors include:

Universal Selector (*): Targets all elements.
Type Selector: Targets elements by tag name (e.g., div, p).
Class Selector (.): Targets elements with a specific class.
ID Selector (#): Targets a unique element with a specific ID.
Attribute Selector: Targets elements with specific attributes.
Group Selector: Combines multiple selectors with commas.

p.intro  

#header

9. What is the difference between descendant selector and child selector?

Sample Answer: Both selectors help target nested elements but with different scopes:

Descendant Selector (space): Targets all nested elements regardless of depth.
Child Selector (>): Targets only direct child elements.

Example:

/* Descendant Selector */
div p  

/* Child Selector */
div > p

Use descendant selectors when you want to style deeply nested elements, and child selectors for direct children only.

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

Sample Answer: These CSS position values control how an element is placed within the document:

Relative: Positions the element relative to its normal position.
Absolute: Positions the element relative to the nearest positioned ancestor.
Fixed: Positions the element relative to the browser window, making it stay in the same place during scroll.

div.relative  

div.absolute  

div.fixed

11. How does z-index work in CSS positioning?

Sample Answer: The z-index property in CSS determines the stacking order of positioned elements along the Z-axis (front-to-back). A higher z-index value means the element will appear in front of elements with lower values.

Important points:

– z-index works only on positioned elements (relative, absolute, fixed, or sticky).
– Default stacking order is based on HTML flow if z-index is not defined.

div.box1  

div.box2

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

Sample Answer: Both properties hide elements, but they behave differently:

visibility: hidden: Hides the element but still occupies space in the layout.
display: none: Completely removes the element from the layout, making other elements shift as if it doesn’t exist.

div.hidden  

div.none

13. What are Attribute Selectors in CSS?

Sample Answer: Attribute selectors target elements based on their attributes and attribute values.

Examples include:

[type="text"] – Targets input elements with type text.
[href^="https"] – Targets links starting with https.
[alt$=".jpg"] – Targets image elements with alt text ending with .jpg.

input[type="text"]

14. How do you center an element horizontally using CSS?

Sample Answer: There are several ways to horizontally center elements:

Using Margin Auto (for block elements):

div.center

Using Flexbox:

div.container

These methods are widely used for centering content within containers.

CSS Flexbox and Grid Interview Questions

15. What is Flexbox in CSS and why is it used?

Sample Answer: Flexbox (Flexible Box Layout) is a one-dimensional layout model in CSS used to align and distribute space among items inside a container, even when their size is unknown.

It helps solve common layout issues like vertical centering, equal spacing, and dynamic element resizing. Flexbox works efficiently for layouts that require alignment either in rows or columns.

.container

16. What is the difference between Flexbox and CSS Grid?

Sample Answer: The key difference lies in layout direction:

Flexbox: Designed for one-dimensional layouts (either row or column).
CSS Grid: Designed for two-dimensional layouts (both rows and columns simultaneously).

Flexbox is ideal for aligning items along a single axis, while Grid handles complex layouts with both rows and columns.

/* Flexbox example */
.container  

/* Grid example */
.container

17. What is justify-content in Flexbox?

Sample Answer: The justify-content property in Flexbox controls horizontal alignment along the main axis.

Common values include:

flex-start – Items align to the start.
center – Items align to the center.
flex-end – Items align to the end.
space-between – Items have equal space between.
space-around – Items have space on both sides.

.container

18. How do you center content vertically and horizontally using Flexbox?

Sample Answer: Flexbox makes centering both vertically and horizontally straightforward.

You need to set both justify-content and align-items to center on the flex container:

.container

This will perfectly center the child element inside the container both ways.

19. What is grid-template-columns in CSS Grid?

Sample Answer: The grid-template-columns property defines the number and size of columns in a CSS Grid layout.

You can use fixed widths, percentages, or flexible units like fr:

.container

This creates three columns: the first is 200px wide, and the next two share the remaining space equally.

20. How can you create equal-width columns using CSS Grid?

Sample Answer: To create equal-width columns, you can use fractional units (fr) in CSS Grid.

Example for a 3-column layout:

.container

This distributes the container width equally among all three columns, making it responsive and scalable.

21. How do you control spacing between grid items?

Sample Answer: The grid-gap or modern gap property controls the spacing between grid items (rows and columns).

You can set single or dual values:

.container

Or separately:

.container

This improves layout readability and spacing control in CSS Grid layouts.

CSS Animation and Transitions Interview Questions

29. What is the difference between CSS transitions and CSS animations?

Sample Answer: Both CSS transitions and animations help bring interactivity and motion to web pages, but they serve different purposes.

CSS Transitions are triggered by a user action or state change—like hovering or focusing on an element. They animate from one state to another based on predefined start and end points. Transitions can’t run automatically and rely on a trigger.

CSS Animations, on the other hand, allow multiple keyframes and can start automatically without user interaction. They offer more control with options like looping, delays, and complex motion paths.

/* Example Transition */
.button:hover  

/* Example Animation */
@keyframes slide  
  to  
}
.box

30. How do CSS transitions work?

Sample Answer: CSS transitions allow property changes to occur smoothly over a given duration. Instead of snapping instantly, elements transition between values—like colour, size, or position—when a trigger like :hover or :focus occurs.

Key components of a CSS transition:

Property: Which CSS property will animate (e.g., color, width).
Duration: How long the transition lasts.
Timing Function: Speed curve (linear, ease, etc.).
Delay: Optional wait time before the transition starts.

.box

When you hover or trigger the state change, the animation runs automatically.

31. What are CSS keyframes?

Sample Answer: CSS keyframes define how an animation progresses over time by specifying multiple intermediate steps (frames) between start and end states.

Unlike transitions (which animate between two states only), keyframes let you create complex multi-stage animations with control over exact points during the animation timeline.

Key aspects of keyframes:

You define percentage markers (like 0%, 50%, 100%) for styling at each point.
It allows animations to loop or repeat infinitely.

@keyframes fadeIn  
  to  
}

.box

32. What properties can you animate using CSS transitions and animations?

Sample Answer: Not all CSS properties are animatable. Generally, properties related to visual appearance and positioning can be animated.

Commonly animatable properties include:

Colors: Like color, background-color, border-color.
Sizes: Like width, height, margin, padding.
Positioning: Like top, left, right, bottom.
Opacity: To create fade effects.
Transformations: Like scale(), rotate(), and translate().

Properties like display cannot be animated in CSS.

33. How do you create a fade-in effect using CSS?

Sample Answer: A simple fade-in effect can be created using CSS animations with keyframes targeting the opacity property.

The process:

– Start the element with 0 opacity.
– Gradually increase opacity to 1.

@keyframes fadeIn  
  to  
}

.box

This creates a smooth, visible fade-in when the element loads.

34. What is transition-delay in CSS?

Sample Answer: The transition-delay property defines the amount of time the browser waits before starting a transition after a state change.

It’s useful when you want a lag before the visual effect kicks in.

Example:

.box

Here, the background colour transition will start after 0.3 seconds.

35. How do you loop a CSS animation infinitely?

Sample Answer: To loop an animation endlessly, set the animation-iteration-count property to infinite.

Example use case: a continuously rotating loader icon.

@keyframes spin  
  to  
}

.loader

This keeps the element rotating forever without user interaction.

Advanced CSS Interview Questions for Experienced

36. What is CSS Specificity and how does it affect styling?

Sample Answer: CSS Specificity is a set of rules that determine which CSS selector takes precedence when multiple rules target the same HTML element.

Specificity is calculated based on the type of selectors used:

Inline styles (highest priority)
IDs
Classes, attributes, pseudo-classes
Elements and pseudo-elements (lowest priority)

For example, a rule using an ID selector will override rules using classes or elements.

/* Higher specificity because of ID */
#header  

/* Lower specificity */
.header

Even if the class is defined later in the CSS file, the ID will still take priority due to higher specificity.

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

Sample Answer: CSS positioning determines how an element is placed in the layout.

Relative: The element is positioned relative to its normal static position. Offset using top, left, right, or bottom won’t affect other elements.
Absolute: The element is positioned relative to its nearest positioned ancestor (other than static). It is removed from normal flow and doesn’t affect surrounding elements.
Fixed: The element is positioned relative to the browser window (viewport). It remains fixed in place even when scrolling.

Understanding positioning is critical when creating complex layouts or sticky UI components.

38. What is the z-index property and how does stacking context work?

Sample Answer: The z-index property controls the vertical stacking order of elements on the z-axis.

Higher z-index values bring elements visually in front of those with lower values.

Stacking context is formed when:

An element has a position other than static and a defined z-index.
CSS properties like opacity (less than 1), transform, or filter are used.

Managing stacking contexts is essential for modal dialogs, dropdowns, or overlapping layers.

.modal

39. What is Critical CSS and why is it important for performance?

Sample Answer: Critical CSS refers to the minimal CSS required to render the visible part of a web page (above the fold) as quickly as possible.

By inlining critical CSS within the HTML document and deferring the loading of non-critical CSS, developers can significantly improve page load times and Core Web Vitals like First Contentful Paint (FCP).

This approach is especially useful for improving SEO and UX on mobile devices.

Many performance tools and frameworks offer plugins for Critical CSS extraction and inlining.

40. Explain the concept of CSS Variables (Custom Properties).

Sample Answer: CSS Variables (also called Custom Properties) allow you to define reusable values that can be referenced throughout your stylesheet.

Benefits include easier maintenance, theme management, and dynamic styling.

Syntax example:

:root  

.button

You can even change variable values using JavaScript for dynamic styling.

41. What is the difference between rem and em units in CSS?

Sample Answer: Both rem and em are relative length units in CSS but differ in reference point.

em: Relative to the font-size of the nearest parent element.
rem: Relative to the root HTML element’s font-size.

For consistent scaling across the site, rem is often preferred, especially in responsive designs.

html  
h1

42. How can you implement a CSS reset, and why is it important?

Sample Answer: A CSS reset removes inconsistent browser-default styling (like margins, padding, headings) to provide a clean base for consistent cross-browser design.

Popular reset methods include:

Global Reset: Using *
Normalize.css: A more refined library that preserves useful defaults while correcting inconsistencies.
Custom Resets: Tailored CSS resets based on project needs.

Applying a reset is one of the first steps when starting a new web project to avoid layout bugs across browsers.

CSS Scenario-Based Interview Questions

43. How would you vertically and horizontally center a div inside its parent?

Sample Answer: Centering a div both vertically and horizontally is a common CSS layout task with multiple solutions depending on the use case.

Two widely accepted methods are:

Using Flexbox:

Set the parent container as display: flex;
Use justify-content: center; and align-items: center;

.parent

Using CSS Grid:

.parent

Both methods are responsive and browser-friendly.

44. How do you create a full-width responsive image that maintains its aspect ratio?

Sample Answer: To make an image responsive and maintain its aspect ratio across different screen sizes, use the following CSS approach:

Set the image width to 100% of its container.
Set the height to auto to maintain the original aspect ratio.
Ensure the container’s width scales responsively.

img

This ensures the image adjusts to the container while preventing distortion.

45. How would you troubleshoot a floated element breaking out of its container?

Sample Answer: This is a classic CSS layout issue. When child elements inside a container are floated, the container loses track of their height, causing it to collapse.

The solution is to clear the floats. Popular techniques include:

1. Clearfix Method:

.container::after

2. Using overflow:

.container

Both techniques force the parent container to recognize the floated children’s height.

46. How would you make a sticky header that stays at the top while scrolling?

Sample Answer: A sticky header is a common UX pattern in modern web design.

You can achieve this using the position: sticky; property:

header

Key points:

top: 0 ensures the header sticks at the top.
z-index keeps it above other elements.
Always set a background colour to prevent content bleed-through while scrolling.

47. How would you handle text overflow with ellipsis for a single line?

Sample Answer: When dealing with long text content that shouldn’t overflow, CSS provides a clean solution with ellipsis.

Here’s the standard approach:

.text-ellipsis

This will cut off the text and add “…” when it exceeds the container width. Ideal for headings, buttons, or table cells where space is limited.

CSS Performance and Best Practices Interview Questions

48. How can you optimise CSS performance for faster page loads?

Sample Answer: CSS performance impacts both page speed and SEO ranking. Here are common optimisation strategies:

Minify CSS: Remove whitespaces, comments, and unnecessary characters using tools like CSSNano or CleanCSS.
Combine CSS Files: Reduces HTTP requests by consolidating multiple CSS files into one.
Use Critical CSS: Inline only above-the-fold styles in the HTML and defer the rest.
Eliminate Unused CSS: Tools like PurifyCSS or UnCSS help remove unused selectors.
Use CSS shorthand: Reduce file size by using concise syntax.

/* Example shorthand */
margin: 10px 20px;

Implementing these CSS performance best practices helps reduce render-blocking issues and improve Core Web Vitals scores.

49. Why should you avoid using !important in CSS?

Sample Answer: While !important can force a CSS rule to override others, it breaks the natural cascade and makes future maintenance harder.

Problems with overusing !important:

Makes debugging complex and unpredictable.
Causes specificity conflicts later when you need to override styles again.
Violates clean coding standards in CSS architecture.

The best practice is to use more specific selectors or adjust CSS architecture (BEM, SMACSS) to control styling without relying on !important.

/* Not recommended */
.button

50. What is the best way to handle large-scale CSS projects?

Sample Answer: Managing CSS at scale requires both strategic planning and clean coding practices.

Best approaches include:

Use a CSS Methodology: Such as BEM (Block, Element, Modifier), OOCSS, or SMACSS for predictable naming conventions.
Modular CSS: Break styles into smaller, component-based files.
Preprocessors: Use Sass or LESS for variables, nesting, and mixins.
Leverage CSS Variables: For theme consistency and easier updates.
Version Control: Maintain stylesheets in Git or other SCM tools for collaboration.

By following these CSS best practices, teams can build scalable, maintainable, and performant front-end architectures.

Frequently Asked Questions on CSS Interview Questions

🔽 What are the most commonly asked CSS interview questions for freshers?

Freshers are usually asked basic CSS interview questions covering selectors, box model, positioning, and media queries. Understanding syntax and practical use cases for each CSS property is essential.

🔽 How do I prepare for advanced CSS interview questions?

Focus on topics like specificity, flexbox, grid layouts, responsive design, animations, and performance optimisation. Practise explaining concepts clearly with real-world examples and scenarios.

🔽 Do companies ask coding-based CSS scenario questions?

Yes. Employers often test your problem-solving skills with CSS scenario-based questions like centering elements, handling text overflow, or fixing layout issues. Be ready to write small code snippets.

🔽 What’s the difference between inline, internal, and external CSS?

Inline CSS: Added directly to HTML elements using the style attribute.
Internal CSS: Defined inside a <style> tag in the HTML head.
External CSS: Written in a separate .css file and linked to the HTML.

External CSS is preferred for large websites for better maintainability and caching benefits.

🔽 Are CSS interview questions different for experienced professionals?

Yes. CSS interview questions for experienced candidates focus more on optimisation techniques, architecture patterns, performance tuning, advanced layout systems like CSS Grid, and complex animations.

CSS Interview Questions and Answers: Top 50 [2025]