โœ… Part 3: Top 30 CSS Interview Questions and Answers (Beginner to Advanced) โ€“ Real Interview Style

Payal PorwalPayal Porwal
6 min read

Table of contents

In this article, youโ€™ll find 30 real-life CSS interview questions for frontend developers. These questions are asked in interviews from fresher to experienced level. Each question is deeply connected to the next, forming a logical learning path. Answers are written in easy and professional English so you can remember and explain confidently during interviews.


๐Ÿ”ฐ Beginner Level CSS Interview Questions (1โ€“10)


1. What is CSS and why do we use it?

Answer: CSS stands for Cascading Style Sheets. We use it to style HTML elements โ€” such as colors, fonts, spacing, layout, etc. Without CSS, web pages would look plain and boring.


2. What are the different types of CSS?

Answer:

  • Inline CSS โ€“ written inside an HTML tag using the style attribute.

  • Internal CSS โ€“ written inside <style> tags in the <head> section.

  • External CSS โ€“ written in a separate .css file and linked using <link> tag.


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

Answer:

  • .class can be used on multiple elements.

  • #id is unique and used for one element only.
    Example:

.red { color: red; }   /* class */
#header { font-size: 24px; }  /* id */

4. What is the Box Model in CSS?

Answer:
The CSS box model represents how every HTML element is structured:

  • Content โ†’ Padding โ†’ Border โ†’ Margin
    Each part affects the elementโ€™s space and layout.

5. What is the difference between padding and margin?

Answer:

  • padding: space inside the element, between content and border.

  • margin: space outside the element, between border and other elements.


6. What are pseudo-classes in CSS?

Answer:
Pseudo-classes define a special state of an element.
Example: :hover, :focus, :first-child

button:hover {
  background-color: blue;
}

7. How do you make a website responsive using CSS?

Answer:
You can use:

  • Media Queries (@media)

  • Flexible layouts (like percentages or vw, vh)

  • Flexbox and Grid
    Example:

@media (max-width: 768px) {
  .container {
    flex-direction: column;
  }
}

8. What are the units used in CSS?

Answer:

  • Absolute: px, cm, mm, in

  • Relative: em, rem, %, vw, vh


9. What is the difference between em and rem?

Answer:

  • em: relative to the parent elementโ€™s font size.

  • rem: relative to the root (html) font size.


10. What is specificity in CSS?

Answer:
Specificity is a set of rules that determine which CSS rule is applied when multiple rules target the same element.
Order of power:

  1. Inline style (style="...")

  2. ID selectors (#id)

  3. Class selectors (.class)

  4. Element selectors (div, p)


๐Ÿš€ Intermediate to Advanced CSS Interview Questions (11โ€“30)


11. What is Flexbox in CSS?

Answer:
Flexbox (Flexible Box) is a layout module in CSS that allows you to arrange items in rows or columns easily, even when their size is dynamic.


12. What are the main properties of a Flex container?

Answer:
Set on the container using display: flex;

  • flex-direction

  • justify-content

  • align-items

  • flex-wrap

  • align-content


13. What does justify-content do in Flexbox?

Answer:
It controls the horizontal alignment of flex items.
Values:

  • flex-start, flex-end, center, space-between, space-around, space-evenly

14. What is align-items used for in Flexbox?

Answer:
It aligns items vertically in the container.
Values:

  • stretch (default), flex-start, flex-end, center, baseline

15. How is align-self different from align-items?

Answer:

  • align-items applies to all items in the container.

  • align-self overrides alignment for a specific item only.


16. What is the use of flex-grow, flex-shrink, and flex-basis?

Answer:
These control how flex items grow, shrink, and take up space:

  • flex-grow: how much it can grow

  • flex-shrink: how much it can shrink

  • flex-basis: default size before space is distributed


17. What is the shorthand for these properties?

Answer:
You can write them as:

flex: 1 0 200px; /* grow shrink basis */

18. What is CSS Grid and how is it different from Flexbox?

Answer:

  • Flexbox: One-dimensional layout (row or column)

  • Grid: Two-dimensional layout (rows and columns)

Use Grid for complex layouts and Flexbox for smaller components.


19. How do you define a CSS Grid container?

Answer:

display: grid;
grid-template-columns: 1fr 1fr 1fr;
grid-template-rows: auto auto;

20. What are Grid lines, Grid tracks, and Grid areas?

Answer:

  • Grid lines: vertical and horizontal lines that divide the grid.

  • Grid tracks: space between two lines (rows or columns).

  • Grid area: rectangular space formed by joining tracks.


21. What are media queries and why are they used?

Answer:
Media queries allow you to apply different styles based on device width, height, resolution, etc.
They make websites responsive.


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

Answer:

  • relative: moves from original position.

  • absolute: positions from the nearest positioned ancestor.

  • fixed: always fixed to the viewport.


23. What is z-index and how does it work?

Answer:
z-index controls the stacking order of elements. Higher z-index means it will appear on top.


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

Answer:

  • visibility: hidden hides the element but still takes up space.

  • display: none removes the element from the layout.


25. What are transitions in CSS?

Answer:
Transitions allow you to smoothly change properties over time.
Example:

button {
  transition: background-color 0.3s ease;
}

26. What are CSS animations?

Answer:
Animations let you define keyframes for styling changes over time.

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

27. What is the difference between min-width, max-width, and width?

Answer:

  • width: fixed value.

  • min-width: minimum allowed width.

  • max-width: maximum allowed width.

They help in responsive design.


28. What is the difference between auto, initial, and inherit in CSS?

Answer:

  • auto: browser decides the value.

  • initial: resets to default value.

  • inherit: inherits value from the parent.


29. How to improve CSS performance?

Answer:

  • Use shorthand properties

  • Minimize CSS file size

  • Avoid unnecessary selectors

  • Use class names instead of element selectors

  • Combine files and use caching


30. Which is better for layouts: Flexbox or Grid?

Answer:
It depends on the design:

  • Use Flexbox for 1D layouts (navbar, buttons row)

  • Use Grid for 2D layouts (entire page layout)

Both can be used together in real-world projects.


โœ… Conclusion

These 30 CSS interview questions are picked from real interview experiences. They are interlinked, progressing from beginner to expert level, and they will help you explain clearly during actual interviews. Practice the answers, try them in real code, and keep experimenting with CSS properties.


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Stay curious. Keep building. ๐Ÿš€

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Written by

Payal Porwal
Payal Porwal

Hi there, tech enthusiasts! I'm a passionate Software Developer driven by a love for continuous learning and innovation. I thrive on exploring new tools and technologies, pushing boundaries, and finding creative solutions to complex problems. What You'll Find Here On my Hashnode blog, I share: ๐Ÿš€ In-depth explorations of emerging technologies ๐Ÿ’ก Practical tutorials and how-to guides ๐Ÿ”งInsights on software development best practices ๐Ÿš€Reviews of the latest tools and frameworks ๐Ÿ’ก Personal experiences from real-world projects. Join me as we bridge imagination and implementation in the tech world. Whether you're a seasoned pro or just starting out, there's always something new to discover! Letโ€™s connect and grow together! ๐ŸŒŸ