CSS Interview Questions and Answers

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Most Frequently Asked CSS Interview Questions

1. What are the CSS frameworks?
2. What are the properties of Flexbox?
3. What are the advantages and disadvantages of using external style sheets?
4. How can embedded style be linked with HTML documents?
5. What is the syntax to link an external style sheet?
6. What are the advantages of using CSS?
7. Describe the effects of the CSS box model on layout.
8. How can you include CSS in a web page?
9. What are the different types of selectors in CSS?

CSS stands for cascading style sheets. They allow you to add style to your web pages. CSS is among the most essential features in the field of web development. This blog comprises all the significant interview questions that you may encounter during your job interview. Excel in your career by preparing yourself for job interviews through these CSS interview questions:

Basic CSS Interview Questions for Freshers

1. What are the CSS frameworks?

Some popular CSS frameworks are:

1. Semantic UI
2. Tailwind CSS
3. Materialize CSS
4. Primer
5. Foundation
6. Gumby
7. Ukit
8. Bootstrap etc

2. What are the advantages and disadvantages of using external style sheets?

The advantages of using external style sheets are as follows:

• Styles of numerous documents can be organized from one single file.
• Classes can be made for use on numerous HTML element types in many forms of the site.
• In complex contexts, methods such as selector and grouping can be implemented to apply styles.

The disadvantages of using external style sheets are as follows:

• An extra download is necessary to import style information for each file.
• The execution of the file may be deferred till the external style sheet is loaded.
• While implementing style sheets, we need to test web pages with multiple browsers in order to check compatibility issues.

3. What are the advantages and disadvantages of embedded style sheets?

The advantages of embedded style sheets are as follows:

• In embedded style sheets, it is possible to generate classes for use on multiple tag types in a document.
• In embedded style sheets, in comparison to external style sheets, no extra download is compulsory to import the information.

The disadvantage of embedded style sheets are as follows:

• In embedded style sheets, controlling the styles for multiple files from one file is not possible.

4. How can you include CSS in a web page?

There are different ways by which you can include a CSS in a web page:

• External Style Sheet: An external file is linked to the HTML document using the link tag.

  <link rel="stylesheet" type="text/css" href="mystyles.css" />
  

• Embed CSS with a Style Tag: Another way to include CSS in a web page is by having a set of CSS styles included within the HTML page.

  <style type="text/css">
  /*Add style rules here*/
  </style>
  

  The CSS rules have to be added between the opening and closing style tags. The CSS is written exactly like the standalone style-sheet files.

• Inline Styles to HTML Elements: Style can be added directly to the HTML element with the help of a style tag.

  <h2 style="color:red;background:black">Inline Style</h2>
  

• Import a Style-sheet File: Another way to add CSS is by using the @import rule. Here, an external file is imported to another CSS file. This is for adding a new CSS file within the CSS itself.

  import "path/to/style.css";
  

5. What are the different types of selectors in CSS?

A CSS selector in a CSS rule set helps select the content that needs to be styled. The different types of selectors are listed below:

• Universal Selector: The universal selector selects all elements on a page. The provided styles will get applied to all the elements on the page.

  * {
    color: "green";
    font-size: 20px;
    line-height: 25px;
  }
  

• Element Type Selector: The element type selector selects one or more HTML elements of the same name. In the example below, the provided styles will be applied to all the ul elements on the page.

  ul {
    line-style: none;
    border: solid 1px #ccc;
  }
  

• ID Selector: The ID selector is used for selecting any HTML element that has an ID attribute same as the selector. In the below example, the assigned styles will get applied to all the elements having the ID container.

  #container {
    width: 960px;
    margin: 0 auto;
  }
  <div id="container"></div>
  

• Class Selector: The class selector choses all the page elements with class attributes that are set to the same value as the class. The styles get applied to all the elements having the same ID on the page.

  .box {
    padding: 10px;
    margin: 10px;
    width: 240px;
  }
  <div class="box"></div>
  

• Descendant Combinator: The descendant selector or, more accurately, the descendant combinator lets you combine two or more selectors and be more specific in the selection method.

  #container .box {
  float: left;
  padding-bottom: 15px;
  } 
  <div id="container">
  <div class="box"></div>
  <div class="box-2"></div>
  </div>
  <div class=”box”></div>
  

  In the above example, the declaration block applies to all elements having a class, “box”, that is inside an element with the ID, “container”.  It is worth noting that the .box element does not have to be an immediate child; there can be another element wrapping the .box, and the styles will still apply.

• Child Combinator: The child combinator is similar to the descendant combinator, except it only targets immediate child elements.

  #container> .box {
  float: left;
  padding-bottom: 15px;
  }
  <div id="container">
  <div class="box"></div>
  <div>
  <div class="box"></div>
  </div>
  </div>
  

  The selector will match all elements that have a class, “box”, and are immediate children of the element, “container”.

• General Sibling Combinator: The general sibling combinator matches elements based on sibling relationships. The selected elements are adjacent to each other in HTML.

  h2 ~ p {
  margin-bottom: 20px;
  }
  <h2>Title</h2>
  <p>Paragraph example.</p>
  <p>Paragraph example.</p>
  <p>Paragraph example.</p>
  <div class=”box”>
  <p>Paragraph example.</p>
  </div>
  

  In the above example, all paragraph elements, (<p>), will be styled with the specified rules, but only if they are siblings of <h2> elements. Even if there are other elements in between <h2> and <p>, the styles will still apply.

• Adjacent Sibling Combinator: The adjacent sibling combinator is almost the same as the general sibling selector but the targeted element must be an immediate sibling, not just a general sibling. The adjacent sibling combinator uses the plus symbol, (+).

  p + p {
  text-indent: 1.Sem;
  margin-bottom: 0;
  }
  <h2>Title</h2>
  <p>Paragraph example.</p>
  <p>Paragraph example.</p>
  <p>Paragraph example.</p>
  <div class=”box”>
  <p>Paragraph example.</p>
  <p>Paragraph example.</p>
  </div>
  

  In the above example, the specified styles will apply only to those paragraph elements that immediately follow other paragraph elements. This means that the first paragraph element on a page will not receive these styles.If there are other elements appearing between two paragraphs, the styles will not apply to the second paragraph.

• Attribute Selector: The attribute selector targets elements based on the presence and/or value of HTML attributes. It is declared using square brackets.

  input [type=”text”] {
  background-color: #444;
  width: 200px;
  }
  <input type="text">
  

6. What is the difference among inline, inline-block, and block elements?

Block Element: Block elements always start on a new line and occupy an entire row or width. Examples of block elements are <div> and <p>.

Inline Elements: Inline elements do not start on a new line; they appear on the same line as the content and tags beside them. Some examples of inline elements are <a>, <strong>, <span>, and <img>.

Inline-block Elements: Inline-block elements are similar to inline elements, but they can have padding, margins, and set height and width values.

7. What are pseudo elements and pseudo classes?

Pseudo elements help to create items that do not normally exist in the document tree. The examples of pseudo elements are:

• ::before
• ::after
• ::selection
• ::first-letter
• ::first-line

Pseudo classes select regular elements under specific conditions such as when a user is hovering over a link. The examples of pseudo classes are:

• :hover
• :active
• :link
• :visited
• :focus

8. What are the differences between adaptive design and responsive design?

9. What are the properties of Flexbox?

The numerous characteristics of CSS Flexbox can be used to create intricate and powerful compositions.

• display is used to describe a flex container. The flex value is utilized to establish a flex container.
• flex-direction is employed to determine the direction of the primary axis, which is the axis that flex items are arranged along. This property can have the values row, row-reverse, column, and column-reverse.
• justify-content aligns flex items parallel to the primary axis. This property can take many different values, including flex-start, flex-end, center, space-between, space-around, and space-evenly.
• align-items align flex items perpendicular to the primary axis. Flex-start, flex-end, center, baseline, and stretch are all possible values for this attribute.
• flex wrap determines whether or not flex items should wrap when their width exceeds the width of the flex container. This property’s possible values are nowrap, wrap, and wrap-reverse.
• align-content, When there is extra space in the flex container, use align-content to align flex lines perpendicular to the major axis. This property’s likely values are flex-start, flex-end, center, space-between, space-around, and stretch.
• flex is employed to establish the flex grow, flex shrink, and flex basis of a flex item. The shorthand property flex creates all three values at the same time. The individual properties are flex-grow, flex-shrink, and flex-basis.

CSS Interview Questions for Experienced (2 to 5 Years)

10. What is the difference between physical and logical tags?

Logical tags mainly focus on the content and are older as compared to the physical tags. Logical tags are hardly used in terms of presentation. In terms of aesthetics, logical tags do not serve any purpose. However, physical tags find their application in presentation.

11. What is the syntax to link an external style sheet?

An external style sheet comprises style description that can be linked with the HTML document externally. An external style sheet is one of the best and most organized ways to keep the style separate from the structure.

The syntax for linking an external style sheet is as follows:

<HTML>
<HEAD>
<LINK REL=STYLESHEET HREF="Test.css" TYPE="text/css">
</HEAD>
</HTML>

12. How can embedded style be linked with HTML documents?

Embedded style can be implemented within HTML code. It is written using the <Style> tag and used under the <Head> structure.

Its syntax is as follows:

<HEAD>
<STYLE TYPE=”text/css”>
style {text-indent: 15pt;}
style1{text-color: #060000;}
</STYLE>
</HEAD>

13. Why is the imported function an easy way to insert a file?

The syntax is shown by coding as:

<Link Rel=Stylesheet Href=”Main.Css” Type=”Text/Css”>
<STYLETYPE=”text=css”>
<!–
@import url(http://www.xyz.css);
…. your code
–>
</STYLE>

The <!– –> tag is used as a comment for browsers that do not support CSS.

14. What are the advantages of using CSS?

The main advantages of using CSS are:

• Separation of Content from Presentation: CSS enables presentation of the same content in multiple formats for mobile, desktop, or laptop.
• Bandwidth: When CSS is used effectively, the browser cache can store the style sheets and these can be used on multiple pages without the need to redownload.
• Easy to Maintain: By making small changes, CSS can be used to completely change the look and feel of a web page. For a global change, we simply have to change the style, and all elements in all web pages will be automatically updated.

15. How is border-box different from content-box?

The border-box property contains the content, border, and padding in height and width properties. If you look at the example below, the box-sizing for the div element is set as border-box. The height and width considered for the div content will also include the padding and border:

div{
    width:300px;
    height:200px;
    padding:15px;
    border: 5px solid grey;
    margin:30px;
    -moz-box-sizing:border-box;
    -webkit-box-sizing:border-box;
    box-sizing:border-box;
}

The actual height of the div content in this case is:

actual height = height - 
                padding on top and bottom - 
                border on top and bottom
              = 200 - (15*2) - (5*2) 
              = 160 px
The actual width of the div content in this case is:
actual width  = width - 
                padding on right and left - 
                border on right and left
              = 300 - (15*2) - (5*2) 
              = 260 px

Let us take a look at the border-box model for the above example:

Content-box, on the other hand, is the default value box-sizing property. Height and the width properties do not include border and padding and only have content. For example:

div{
    width:300px;
    height:200px;
    padding:15px;
    border: 5px solid grey;
    margin:30px;
    -moz-box-sizing:content-box;
    -webkit-box-sizing:content-box;
    box-sizing:content-box;
}

Here, content-box is the box-sizing for the div element. The height and width for the div content do not include padding and border. The full height and width parameters are specified for the content as shown below:

16. Explain RGB stream

RGB represents the colors in CSS. The RGB streams are namely red, green, and blue. The intensity of the colors can be set from 0 to 255. It enables CSS to have a spectrum of visible colors.

17. Define z-index

Z-index helps specify the stack order of elements that overlap each other. While the default value of z-index is zero, it can take both positive and negative values. An element with a greater stack order is always above the element with a lower stack order.

Z-index can assume the following values:

• auto: It sets the stack order equal to its parents.
• number: It sets the stack order of the element. Negative values are allowed.
• initial: It sets this property to its default value.
• inherit: It inherits this property from its parent element.

18. Name the different ways to position some aspects in CSS

The positioning method type is determined by the positioning property. The five different position values are:

• fixed
• static
• absolute
• sticky
• relative

The elements are positioned with the help of top, left, right, and bottom properties. These properties need to be set first, and they work depending on position value.

19. What is the property that is used to control image scroll?

The background-attachment property is used to set whether the background image remains fixed or is scrollable with the rest of the page. Here is an example for a fixed background-image:

body {
  background-image: url(‘url_of_image’);
  background-repeat: no-repeat;
  background-attachment: fixed;
}

20. In CSS, what are pseudo-classes? Give an illustration.

Pseudo-classes are keywords that specify a special state of an element. An example is the :hover pseudo-class, which applies styles when the mouse is over an element. 

For instance,

 
a:hover {
    color: red;
}

21. What distinguishes visibility: hidden from display: none?

Display: none eliminates an element from the layout, preventing it from showing up on the page or occupying any space. 

Visibility: hidden makes the element invisible, although it still takes up room in the arrangement.

22. In CSS, how can an element be centered vertically?

.container {
    display: flex;
    justify-content: center; /* horizontally center */
    align-items: center; /* vertically center */
    height: 100vh; /* adjust as needed */
}

23. Why would you use a CSS preprocessor such as Sass or Less?

Preprocessors for CSS add features like variables, nesting, mixins, and functions to extend the possibilities of CSS. They make stylesheets more scalable and maintainable.

24. How may CSS be used to create a responsive design?

Responsive design can be achieved using CSS media queries to apply different styles based on the device’s screen size or orientation.

 
@media screen and (max-width: 600px) {
    /* Styles for small screens */
}

25. What distinguishes inline display attributes from inline-block display properties?

Inline elements don’t begin on a new line; instead, they flow with the surrounding content. Two instances are <span> and <a>.

Similar to inline elements, inline-block elements can also have height/width, padding, and margin values. They can be positioned using the top, bottom, left, and right attributes and do not begin on a new line.

26. Why is the CSS z-index attribute used?

The stacked order of positioned items is managed by the z-index attribute. It describes an element’s stack order in relation to other elements on the page. Elements with lower z-index values are stacked underneath those with higher z-index values.

27. How do you create a CSS animation?

 
@keyframes slidein {
    from {
        transform: translateX(-100%);
    }
    to {
        transform: translateX(0);
    }
}

.element {
    animation: slidein 1s ease-in-out;
}

28. What are sprites in CSS? How can website performance be enhanced?

CSS sprites use CSS to display particular portions of a picture by combining many images into a single image. By lowering the quantity of HTTP requests needed to load many images, they enhance website performance by speeding up page loads.

29. What is the overflow attribute in CSS used for?

The handling of material that extends beyond the boundaries of its contained element is determined by the overflow attribute. It has four settings: scroll, auto, hidden, and visible.

30. Describe the advantages of the CSS grid layout paradigm.

A two-dimensional layout method for grouping elements in rows and columns is the CSS grid layout. When compared to more conventional techniques like flexbox or floats, it offers a more potent and adaptable way to design grid-based layouts. The precise arrangement and alignment of items within a grid are made possible by grid layout.

31. How can a responsive navigation menu be made with CSS?

One method for making the navigation menu’s layout flexible is to utilize CSS flexbox or CSS grid. The menu’s style and layout can then be modified using media queries in accordance with the screen size. For improved usability, other methods, such as employing the checkbox hack to hide the menu behind a toggle button on smaller screens, might be utilized.

32. How do you create a sticky header using CSS?

 
@keyframes slidein {
    from {
        transform: translateX(-100%);
    }
    to {
        transform: translateX(0);
    }
}

.element {
    animation: slidein 1s ease-in-out;
}

33. Describe the effects of the CSS box model on layout.

The organization of the items on a web page is described by the CSS box model. Content, padding, border, and margin make up its components. Text and images are displayed in the content area, which is surrounded by a border; the space outside the border is known as the margin. Padding is the area that appears between the content and the border. It determines how an element fits into the layout and how it works with other elements.

34. Describe the advantages of the CSS flexbox layout approach over conventional layout techniques.

A style concept known as CSS Flexible Box style, or flexbox, enables the development of responsive and adaptable layouts with a single-dimensional axis (horizontal or vertical).

Compared to more conventional layout techniques like floats or positioning, it offers a more effective and natural approach to dividing up space and orienting objects inside a container.

Powerful capabilities offered by Flexbox include the ability to quickly rearrange objects, manage space alignment and distribution, and automatically modify the layout according to the amount of available space and the size of the content.

Its benefits include better responsiveness, simpler and cleaner markup, and enhanced support for intricate layouts without the need for workarounds or hacks.

Advanced CSS Interview Questions (6 to 12 Years)

35. How may a responsive design be created without the use of media queries?

• Applying relative measurements for widths, heights, and margins, such as percentages and viewport units (vw, vh)
• Using CSS grids and flexboxs for flexible layouts
• Using proportionate, em, or rem-based font sizes with flowing typography.

36. How can CSS performance be optimized for faster page loading?

• CSS files can be made smaller by minifying them.
• Reducing the number of HTTP requests by combining several CSS files into one file
• Avoiding picks with excessive precision and nesting
• Minimizing the usage of pricey CSS attributes like border-radius and box-shadow
• Reducing the number of server requests by integrating smaller images into a single image using CSS sprites

37. Describe the differences between the CSS selectors :nth-child() and :nth-of-type().

:nth-child(): Regardless of type, this function chooses elements based on where they are in a group of siblings.

:nth-of-type(): Chooses components of a particular type according to where they fall in a sibling group.

38. How can a modal dialogue that uses only CSS be implemented?

To build a modal dialogue without JavaScript, use a combination of CSS sibling selectors and HTML input elements, such as a checkbox. Make use of CSS to display the modal once the input element is checked.

39. Provide examples of when and how to utilize CSS vendor prefixes, along with an explanation of their function.

CSS vendor prefixes are used to add experimental or browser-specific CSS features that may not be fully supported across all browsers.

.box {
  -webkit-border-radius: 10px; /* Safari, Chrome */
  -moz-border-radius: 10px; /* Firefox */
  border-radius: 10px; /* Standard */
}

40. Describe the function of CSS custom properties, often known as variables, and give instances of how to use them.

CSS custom properties, or variables, allow for the definition of reusable values in CSS.

:root {
  --primary-color: #3498db;
}
.button {
  background-color: var(--primary-color);
}

41. Explain the distinction between the transition properties and the CSS transform properties.

Transform gives an element a 2D or 3D transformation (such as rotation, scaling, or translation) without changing the document flow or layout.

Transition animates the change between multiple property values and defines how CSS properties should change over time in response to user actions (e.g., hover, click).

Salary Trends – CSS

CSS Job Trends

Global Demand

According to LinkedIn, there are currently more than 2,000 open positions for a front-end developers in the United States.

Projected Growth

The demand for Frontend Developers is soaring, and web developer employment is expected to surge by more than 20% in 2024. This trend is particularly pronounced, surpassing growth rates in other industries. 

Regional Trends

 In India, where web developer employment is expected to surge by 23% from 2016 to 2026, this trend is particularly pronounced, surpassing growth rates in other industries. The job number has been noted to be above 22,000, according to LinkedIn.

CSS Roles and Responsibility

According to the job posted on Naukri.com by PwC Service Delivery Center,

Role: Front End Developer 

Responsibilities:

• Work together with developers and designers to produce front-end solutions that use JavaScript, SQL, and React JS for cloud deployment.
• Create wireframes and mockups, and modify unique solutions in response to customer input.
• Improve the functionality of websites, fix issues, and record technical procedures.
• Examine the applicability of developing technologies and suggest their strategic deployment.
• To ensure effective and scalable frontend development, conduct root cause analysis and provide solutions.

Skills Required:

• Skilled at practical programming for effective project delivery; knowledgeable in SQL, cloud services, and React JS
• Ability to solve problems creatively, good at setting priorities, and capable of guaranteeing project completion on schedule and within budget
• Experienced in agile approaches, guaranteeing flexible and effective project management
• Proficient in both written and spoken communication, promoting efficient teamwork and transparent project updates
• Exceptional interpersonal abilities that promote positive client and team dynamics

We hope these Full Stack development course interview questions will help you prepare for your upcoming interviews. If you are looking to learn Full Stack developer course in a systematic manner with expert guidance and support then you can check our Full Stack developer course with placement guarantee.