Most Important CSS Interview Questions and Answers

As more businesses opt for the online route, they try to make their web applications and websites attractive, engaging, and user-friendly. Cascading Style Sheet or CSS is a style sheet language that determines how consistent the elements in a web page look and feel. CSS is one of the Top 10 Skills to Become a Full-Stack Developer in 2022.

Here are some of the most essential CSS interview questions. If you are a CSS aspirant, you must familiarize yourself with these CSS interview questions and answers to land your dream job.

CSS Interview Questions For Freshers

1. What are the advantages of using CSS?

• CSS allows presenting the same content in multiple formats. It essentially separates content from presentation.
• The entire web page can be made to look and feel different by only making small changes due to CSS. All elements in the web pages are updated automatically if a change in style is opted for.
• The style sheets can also be stored in the browser cache and used on multiple pages.

2. What are the limitations of CSS?

• Not all style selectors are supported by all browsers. The @styles determines which styles and specific CSS features are supported on a browser.
• CSS also faces cross-browser issues as certain selectors work differently in different browsers.
• As of now, no parent tag can be selected through CSS.
• CSS has no in-built security to safeguard it from being overridden.

3. What are CSS frameworks? Name some of them.

CSS frameworks are libraries that make web design easier and standards-compliant. Bootstrap, Foundation, Bulma, UIkit, Semantic UI, Susy, Materialise, Pure, Skeleton, Milligram, Tailwind CSS, Tacit, Spectre, Primer are some of the most commonly used CSS frameworks.

4. What are the different ways to include CSS in a webpage?

• An external CSS style sheet can be linked to an HTML page using the link tag. Learn How to insert CSS into HTML.
• CSS styles can be embedded within the HTML page with a style tag.
• CSS rules can be Added directly inline to HTML elements using a style tag.
• An external CSS file can be imported within the CSS file using the @import rule.

5. Name the different variations of CSS?

• CSS1
• CSS2
• CSS2.1
• CSS3
• CSS4

6. What are the different types of Selectors in CSS?

The different types of selectors of CSS rule sets are:

• Universal Selector: It selects all the elements on a page.
• Element Type Selector: It matches all the HTML elements of the same name on a given page.
• ID Selector: It matches the ID attribute of an HTML element with that of the selector.
• Class Selector: It matches all elements on a page with their ID attribute the same as a class.
• Descendant Selector or Combinator: It combines two or more selectors.
• Child Combinator: It is similar to descendant combinatory but only targets immediate child elements.
• General Sibling Combinator: It matches elements based on sibling relationships.
• Adjacent Sibling Combinator: It is similar to the general sibling selector, except that the targeted element is an immediate sibling and not a general sibling.
• Attribute Selector: It targets elements based on HTML attributes. It is declared using square brackets.

7. How do Reset CSS and Normalize CSS differ?

Reset CSS resets all elements' characteristics like fonts, margins, and paddings to the same values. In other words, eliminates all built-in browser styling.

Normalize CSS maintains consistency of built-in browser styling across all browsers. Additionally, it rectifies bugs for dependencies on browsers.

8. What are viewport height and viewport width in CSS? How are they measured?

Viewport height (VH) and viewport width (VW) are responsive design procedures. VH and VW are CSS units used to measure percentage height and percentage width, respectively, with reference to the viewport. VH and VW are 1/100th part of the height and width of the viewport, respectively. If the browser is 1000px high and 1000px wide, 1 VH is 10px and 1 VW is 10px.

9. What is a viewport?

Viewport, the visible area for a user, is the area of a web page where the web content is viewed. Also, the viewport is not the same for all devices; it is smaller on mobile phones than on a computer screen.

10. When and why should webpages be tested in different browsers?

Web pages must be tested in different browsers when designing or modifying them. It is crucial to test web pages periodically in other browsers because of the updates and changes in different browsers.

11. What do you understand by cascading in CSS?

If multiple rules apply to an HTML element, the browser must know which style must be applied to the element. This is done by cascading down the list of style declaration elements. Thus, cascading is the process that helps the browser identify, select and apply the most recent and specific style.

12. State the components of CSS Style.

• The selector is an HTML or ID element where the style is applied.
• Property is the type of attribute to be applied.
• The value allocated to the properties.

13. What are the elements of the CSS Box Model?

The CSS box model defines the layout and design of CSS elements. The elements are:

• Content - It denotes the content, like text, images, etc.
• Padding - It is the transparent area around the content.
• Border - It is the area around the padding
• Margin - It is the area around the border.

14. What is the z-index, and how is it used?

It specifies the order of elements that may overlap one another. z-index can take either a positive or negative number, and its default value is zero. Elements with higher z-index are stacked above the ones with lower z-index values.

15. What do you understand about RGB in CSS?

RGB colour values represent red, green, and blue colors. In CSS, the RGB value is specified using: RGB(red, green, blue). Each parameter defines the intensity of the colour between 0 and 255.

In the case of RGB(255, 0, 0), the colour displayed is red since red is set to its highest value, and the others are set to its lowest value 0.

CSS Interview Questions For the Experienced

1. List the modules of CSS3

The key modules are:

• Box Model
• Selectors
• Image Values and Replaced Content
• Backgrounds and Borders
• 2D/3D Transformations
• Text Effects
• Animations
• User Interface
• Multiple Column Layout

2. Is the CSS case sensitive?

CSS style sheets are not case-sensitive. The values of HTML ID and class attributes are case-sensitive.

3. What is the difference between CSS3 and CSS2?

CSS3 has XHTML specification and unlike CSS2, it divides CSS into different modules. CSS3 supports almost all recent web browsers.

4. What are CSS Pseudo-elements?

They are keywords that are used to style specified parts of selected elements.

5. List the different Media types in CSS.

Various media types are used for mobile devices, printers, and computers:

• all: for devices enabled to support all categories of media
• braille: for devices enabled to support braille tactile feedback
• embossed: for printers that support paged braille
• print: for printers
• aural: for sound synthesizers and speech
• projection: projects on projectors
• handheld: for handheld devices
• screen: for colour computer screens
• tty: for media using a fixed-pitch character grid
• tv: for devices that are similar to television

6. What is a CSS preprocessor?

A browser only understands CSS, and many times it is not possible to write clean and reusable rules in multiple selectors. This limitation is overcome by using CSS preprocessor, a scripting language that extends CSS. It advances the basic functionalities of CSS, which is later compiled into a normal CSS code that the browser can comprehend.

7. What are SASS, LESS, and Stylus?

• SASS: It stands for ‘Syntactically Awesome Style Sheets. Writing different CSS functionalities like variables, mathematical operations, loops, functions, and imports is more effective.
• LESS: It stands for ‘Leaner Stylesheets.’ It is easy to add LESS to any JavaScript project. It uses @ to define the variables.
• Stylus: It adds functionality to native CSS. It is flexible and offers a wide range of functionalities in writing syntax.

8. Explain the different position properties in CSS?

There are five position properties for positioning an element in a CSS layout.

• fixed: The element does not change position with scrolling since it is positioned with respect to the browser window itself.
• static: It forcefully removes the undesired positioning applied to an element.
• relative: It is to position an element relative to the reference element.
• sticky: It is a combination of relative and fixed position properties. An element has a relative position up until a defined threshold. Beyond that, the element has a fixed position.
• absolute: it places an element at the exact desired position. It is determined with respect to the parent element or the page itself if the parent element is unavailable.

9. What are the ways a div can be center-aligned inside another div?

• Centering using Table
• Centering using Transform
• Centering using Flexbox
• Centering using Grid

10. What is the difference between CSS grid layout and flexbox?

The CSS Grid Layout is a 2-dimensional layout, while the flexbox is a 1-dimensional layout. The grid can work on both columns and rows at a given time, unlike the flexbox, which can only handle either of them at a time.

11. What is the ruleset?

It is used for the identification of selectors. It applies a set of properties with some defined values for the element or a specific set of elements used in the HTML page.

12. What is mixin?

Mixins enable the reuse of complex CSS styles and behaviours and apply them to any style rule.

13. What is a declaration block?

It is an ordered collection of CSS properties and values. It contains one or more declarations separated by semicolons.

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

Physical tags only decide the appearance of the text. They do not provide any information about the text. On the other hand, Logical tags describe the text including its behaviour, nature of content and function of text on the page.

15. Why moving elements with transform is better than positioning?

position:relative and transform:translate are CSS2 and CSS3 properties, respectively. The transform:translate property uses hardware acceleration wherever possible so we see better performance if animations or transitions are being used on an element when compared to position: relative.

Conclusion

Web Development is touted to be one of the highest paying jobs of 2022 for freshers. Careers in web development are predicted to grow by 20% by 2022. As interviewers seek highly skilled professionals, you must be thoroughly prepared with these CSS Interview Questions And Answers which are often asked in Full Stack Web Development, Front End Development, or related job interviews.

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