CSS Interview Questions?

In this detailed but easy-to-follow article, we've discussed the most common CSS interview questions and provided answers suitable for both beginners and experienced individuals.

CSS is like the fashion designer of websites. It's all about making web pages look nice by changing colors, shapes, and how things are arranged on the screen. It's what makes websites look good and work well.

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Basic CSS Interview Questions & Answers


1. What is CSS?


CSS stands for Cascading Style Sheet. It is a popular styling language used in conjunction with HTML to create web pages. It is also compatible with any XML document, including plain XML, SVG, and XUL.

2. What are the different versions of CSS?


The CSS versions are as follows:

  1. CSS1
  2. CSS2
  3. CSS3

CSS1 was founded in 1996, which was the first version. The latest CSS version is CSS3, which is the most advanced version with numerous functionalities and features.

3. How do you include CSS on a web page?


Three ways to include CSS in web pages.

  1. The inline approach is used to insert style sheets into an HTML document.
  2. The embedded/internal method applies a distinct style to a single copy.
  3. When you want to make changes on numerous pages, you use the linked/imported/external technique.

4. What are the benefits of CSS?


Some of the primary CSS benefits are:

  1. Improve web page loading speed

    2. CSS helps in getting more output with less code. It reduces the load on the web page, which results in increased page speed.

  2. Enhance User Experience (UX)

    3. The primary role of CSS is to make the pages look appealing and well-designed. Eventually, it improves the experience of the users coming to the site.

  3. Faster Front-End Development

    4. A single string of CSS code can be used for as many pages as you like. It means you don’t have to write the same styling code for all pages. As a result, the time required to design web pages is lower.

  4. Facilitates Responsive Web Design

    5. Responsive web design is not only crucial for user experience across multiple screen sizes but also important for SEO. CSS helps in designing web pages that are compatible across all devices.

5. What are CSS frameworks?


CSS frameworks are pre-created libraries that make web page style more accessible and standard compliant. CSS frameworks that are commonly used are:

  1. Bootstrap
  2. Tailwind CSS
  3. Foundation
  4. Bulma
  5. Skeleton
  6. Ulkit
  7. Milligram

6. Why are the background and color in CSS different properties when they should always be set together?


This is because of two reasons:

  1. It improves the readability of style sheets. The background property in CSS is complex, and when paired with color, the complexity becomes even more.
  2. The color is inherited, but the backdrop is not. As a result, this can add to the uncertainty.

7. What is an embedded style sheet in CSS?


A CSS style specification is an embedded style sheet approach used in conjunction with HTML. Using the STYLE element, you can embed the whole stylesheet in an HTML document.

<style>    

body {    

    background-color: linen;    

}    

h1 {    

    color: red;   

    margin-left: 80px;    

}     

</style>

8. What is a CSS selector?


It is an important part of CSS that allows developers to select the HTML elements that are supposed to be styled with CSS. The following are the main CSS selectors:

  1. CSS Element Selector
  2. CSS Id Selector
  3. CSS Class Selector
  4. CSS Universal Selector
  5. CSS Group Selector

9. What are author style sheets in CSS?


These are style sheets created by the author of the web page. They are what most people think of when they think of CSS-style sheets.

10. What is the difference between padding and margin in CSS?


Margin and padding can be confusing to a fresher developer. After all, in some ways, they seem like the same thing: white space around an image or object.

Padding is the space inside the border and between the border and the actual image or cell contents. Note that padding goes completely around the contents. It can be on the top, bottom, right and left sides.

Margins are the spaces outside the border, between the border and the other elements next to this object.

11. What can be the reasons if a CSS color style is not working?


CSS is written with US English spellings. So if you are writing colour:red; in your style sheets, none of your text will change color.

Make sure that when you write CSS color styles, you use the US English spelling for them:

  1. color
  2. background-color
  3. border-color
  4. outline-color

12. What are some CSS styling elements?


Some CSS Style components are as follows:

  1. Selector
  2. Property
  3. Value

13. What is the significance of CSS opacity?


It is used to specify the transparency of an element. In layman’s terms, it indicates the clarity of the image. Opacity is described as the amount of light that can pass through an item in technical terms.

As an example:

<style>    

img.trans {    

    opacity: 0.4;    

    filter: alpha(opacity=40); /* For IE8 and earlier */    

}    

</style>

14. What is a universal selector in CSS?


Instead of choosing elements of a particular type, the universal selector matches the name of any element type. 

<style>    

* {    

   color: green;    

   font-size: 20px;    

}     

</style>

15. Which command is used to select all of the paragraph’s elements?


The p[lang] command is used to determine all paragraph components. You must know such tricky things while preparing for CSS interview questions and answers for freshers.

16. Which attribute is used to control the background image repetition?


The background-repeat feature causes the background picture to be repeated horizontally and vertically. Specific images are only repeated horizontally or vertically.

<style>    

body {    

background-image: url("paper1.gif");    

margin-left:100px;    

}    

</style>

17. Which property in CSS is used to control the location of the image in the backdrop?


The background-position parameter specifies the position of the backdrop picture at the start. The background image is usually placed in the top-left corner of the webpage.

You can configure the following positions:

  1. center
  2. top
  3. bottom
  4. left
  5. right

18. Which CSS property is used to control the background image scroll?


The background-attachment attribute specifies whether the background picture should be fixed or scroll with the rest of the page in the browser window. If you set the background picture selected, it will not move when you scroll through the browser.

Let’s look at the static background image as an example:

background: white url('bbb.gif');  

background-repeat: no-repeat;  

background-attachment: fixed;

19. What is the difference between CSS class and id selectors?


Class selectors are given an overall block, whereas id selectors accept only one element that differs from other components.

CSS Class Selector

<style>    

.center {    

    text-align: center;    

    color: blue;    

}    

</style>

CSS Id Selector

<style>    

#para1 {    

    text-align: center;    

    color: blue;    

}    

</style>

20. What are the benefits of using external style sheets?


The external style sheets in CSS provide the following benefits:

  1. You can construct classes to reuse them in several documents.
  2. It allows you to control the styles of several documents from a single file.
  3. It is great for applying styles in complex scenarios.

21. Can you explain the difference between inline, embedded, and external style sheets?


  1. Inline Style Sheets

These are used to style a single line of code.

syntax

<htmltag style="cssproperty1:value; cssproperty2:value;"> </htmltag> 
  1. Embedded Style Sheets

Style sheets that are embedded are placed between the head>…/head> tags.

syntax

<style>    

body {    

    background-color: linen;    

}    

h1 {    

    color: red;    

    margin-left: 80px;    

}     

</style>
  1. External Style Sheets

By updating only one style sheet, you may apply the style to all of your website’s pages

syntax

<head>    

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

</head>

22. What is responsive web design or RWD?


RWD is an abbreviation for Responsive Web Design. This strategy is used to correctly show the specified page across all screen sizes and devices, such as a smartphone, tablet, desktop computer, or laptop. It helps you to avoid the need to build a separate page for each device.

23. What is the benefit of using CSS sprites?


A web page containing many photos will take longer to load because each image sends out an HTTP request separately. CSS sprites minimize the loading time of a web page by combining multiple small pictures into a single image. The number of HTTP requests is reduced, as is the loading time.

24. What is the difference between logical and physical tags in CSS?


  1. Presentational markup refers to physical tags, whereas logical elements are irrelevant to appearances.
  2. Physical tags are newer versions, whereas logical tags are older and focus on content.

25. Explain the CSS Box model and what are its components.


CSS box models specify the design and layout of CSS elements.

The components are as follows:

  1. Margin: Margin is the area around the border that is removed. It is unmistakable.
  2. Border: This is the area around the cushioning.
  3. Padding: It eliminates the area around the content. It is transparent.
  4. Content: It means content like text, images, etc.

26. What is the CSS float property?

It is used to move the image to the right or left, as well as the text wrapped around it. It does not affect the properties of the elements used before it.

27. How to use CSS to restore the default property value?

There is no simple way to restore default values to whatever browser is being used. The closest option is the ‘initial’ property value, which restores the default CSS values rather than the browser’s default styles.

28. What is the z-index, and how does it work?


The z-index assists in specifying the stack order of positioned items that may overlap. The z-index has a default value of zero and can be either positive or negative.

A higher z-index element is always stacked above a lower index.


The following are the possible values for Z-Index:

  1. Auto: Makes the stack order the same as its parents.
  2. Number: The number determines the stack order.
  3. Initial: Initializes this property to its default setting (0).
  4. Inherit: This property is inherited from its parent element.

29. What is the difference between visibility: hidden and display: None?


Visibility: hidden hides the element, but it takes up space and interferes with the layout of the content.

<!DOCTYPE html>  

<html>  

<head>  

<style>  

h1.vis {  

    visibility: visible;  

}  

h1.hid {  

    visibility: hidden;  

}  

</style>  

</head>  

<body>  

<h1 class="vis">It is visible</h1>  

<h1 class="hid">It is hidden</h1>  

<p>Note - Second heading is hidden, but it still occupies space.</p>  

</body>  

</html>  

Display: none also hides the element but does not occupy space. It will not affect the layout of the document.

<!DOCTYPE html>  

<html>  

<head>  

<style>  

h1.vis {  

    display: block;  

}  

h1.hid {  

     display: none;  

}  

</style>  

</head>  

<body>  

<h1 class="vis">It is visible</h1>  

<h1 class="hid">It is hidden</h1>  

<p>Note - Second heading is hidden and not occupy space.</p>  

</body>  

</html>  

30. What is W3C?

W3C is an abbreviation for World Wide Web Consortium. Its objective is to give World Wide Web information. It also creates Web rules and guidelines.

31. What is tweening in CSS?


  1. It is the creation of interim frames between two images.
  2. It creates the appearance that the first image proliferated into the second.
  3. It is a vital technique used in all sorts of animation.
  4. To achieve tweening in CSS3, the Transforms (matrix, translate, rotate, scale) module can be used.

32. What’s the difference between CSS2 and CSS3?


The primary difference between CSS2 and CSS3 is that CSS3 is separated into portions known as modules. CSS3 modules, unlike CSS2, are supported by a wide range of browsers.

CSS3 also includes new General Sibling Combinators, responsible for matching sibling elements with supplied elements.


33. What exactly is an RGB stream?

CSS uses RGB to represent colors. Red, Green, and Blue are the three streams. Color intensity is expressed by values ranging from 0 to 256. CSS can now have a wide range of visible colors.


34. What was the goal of creating CSS?

CSS was created to specify how web pages look visually. It enables developers to segregate the structure and content of a website, which was previously impossible.

35. What is the difference between a class and an ID?


Class is a method of customizing HTML components. They are not unique and contain several elements. ID, on the other hand, is unique and can only be assigned to a single element.

36. How to incorporate CSS into an HTML page?


CSS can be integrated into HTML in three ways: utilizing style tags in the head section, inline styling, writing CSS in a separate file, and linking to the HTML page using the link tag.

37. What are the CSS Box Model’s components?


The CSS box model specifies how CSS elements are laid out and designed. For example, content (such as text and images), padding (the area around content), border (the area around padding), and margin are the elements (the area around the border).

38. What do you mean by “universal sector”?


A universal selector matches the name of any element type rather than picking items of a specific type.

Example: 

<style>    

* {    

      color: blue;    

      font-size: 10px;    

}     

</style>

39. What are the characteristics of flexbox?


Flexbox is an abbreviation for the flexible box. It was introduced in CSS in 2017 to provide an efficient approach to handling layouts, aligning elements within them, and distributing gaps amongst the items in dynamic/responsive situations.

In addition, it improves the ability to change the proportions of things and optimally use the available space in the container. CSS3 gives various attributes to help with this.

Flexbox has the following properties:

Flex-direction

This parameter specifies how the container should stack the flex-targeted objects. This property has the following values: 

  1. row: Stacks items in the flex container horizontally from left to right.
  2. Column: Stacks items in the flex container vertically from top to bottom.
  3. Row-reverse: Stacks items in the flex container horizontally from right to left.
  4. Column-reverse: Stacks items in the flex container vertically from bottom to top.

Flex-wrap

This property determines whether or not flex elements should be wrapped. Possible values include:

  1. wrap: If necessary, the flex items would be covered.
  2. nowrap: The default value indicates that the items will not be wrapped.
  3. Wrap-reverse: This specifies that the elements will be wrapped in reverse order if necessary.

Flex-flow

This property sets both the flex-direction and the flex-wrap attributes in a single sentence.

  1. Justify-content: It’s use is for aligning the flex components. Possible values include:
  2. center: This indicates that all flex components are located in the container’s center.
  3. Flex-end: This value ensures the elements are aligned at the container’s end.
  4. Space-around: This value shows the things with space between, before, and around them.
  5. Space-between: This value shows items with lines separated by spaces.

Align-items

It’s use is for flex item alignment.

Align-content

Align the flex lines.


40. Do margin-top and margin-bottom affect inline elements?


No, it does not affect the inline parts. Inline items flow with the page’s content.

41. What are the limitations of CSS?


There are certain CSS limitations you must know:

  1. Ascending with selectors is not possible
  2. Vertical control limitations
  3. There are no expressions
  4. There is no column declaration
  5. Dynamic behavior does not govern the pseudo-class
  6. It is not able to apply rules, styles, or target-specific text