CSS Developer Hiring Guide

Hiring Guide for CSS Engineers

Ask the right questions to secure the right CSS talent among an increasingly shrinking pool of talent.

CSS (Cascading Style Sheets) is a computer programming language developed in 1996 by the World Wide Web Consortium (W3C) to enhance HTML's design capabilities. It is primarily used for describing the look and formatting of a document written in HTML or XML. CSS enables developers to control layout, colors, fonts, and other aspects of web pages that previously could only be partially manipulated through HTML. Over time, CSS has evolved into three levels: CSS1, CSS2, and CSS3 - each introducing new features and improvements over its predecessor. Its widespread adoption across web browsers underscores its pivotal role in modern web design.

First 20 minutes

General CSS knowledge and experience

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

What are pseudo-classes in CSS?

Pseudo-classes in CSS are used to define a special state of an element. For example, :hover can be used to change a button's color when the user's pointer hovers over it.

What is the CSS box model?

The CSS box model is a box that wraps around every HTML element. It consists of: the content, padding, border, and margin.

Describe the difference between 'class' and 'id' in CSS.

In CSS, 'class' can be used to select and style multiple elements, while 'id' is used to select and style a single unique element. 'id' has a higher specificity than 'class'.

How would you include a CSS file in HTML?

You can include a CSS file in HTML using the <link> tag in the <head> section of the HTML file. The href attribute should contain the path to the CSS file.

What are CSS selectors?

CSS selectors are patterns used to select the element(s) you want to style. They can select elements based on their name, id, class, attribute, and more.

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What youre looking for early-on

Has the candidate demonstrated experience with CSS pre-processors like SASS or LESS?

Pre-processors can make CSS more efficient and manageable, so experience with them can be a valuable asset.

Does the candidate show a willingness to learn and adapt?

The field of web development is constantly evolving, so it's important for developers to be able to keep up with new technologies and practices.

Can the candidate work well with others?

Teamwork is often a key part of development, as they will likely need to collaborate with other developers, designers, and stakeholders.

Is the candidate familiar with responsive design principles?

Responsive design is a key aspect of modern web development, ensuring that websites function well on a variety of devices and screen sizes.

Has the candidate demonstrated the ability to solve problems?

Problem-solving skills are crucial in development as they will often need to troubleshoot and fix issues in their code.

Does the candidate have a strong understanding of CSS fundamentals?

This is important because a strong foundation in CSS is necessary for creating and maintaining the visual aspects of a website.

Next 20 minutes

Specific CSS development questions

The next 20 minutes of the interview should attempt to focus more specifically on the development questions used, and the level of depth and skill the engineer possesses.

Describe the difference between 'relative', 'fixed', 'absolute', and 'sticky' positioning in CSS.

'Relative' positioning is positioned relative to its normal position. 'Fixed' positioning is positioned relative to the browser window. 'Absolute' positioning is positioned relative to the nearest positioned ancestor. 'Sticky' positioning is a hybrid of relative and fixed positioning.

How would you use CSS to make a website responsive?

To make a website responsive with CSS, you can use media queries to apply different styles for different screen sizes. You can also use relative units instead of fixed units, and use the viewport meta tag.

What are CSS media queries?

CSS media queries are a technique used for making responsive web designs. They allow you to apply different styles based on the characteristics of the device rendering the web page, such as screen width.

What is the difference between 'block' and 'inline' display values in CSS?

In CSS, 'block' elements start on a new line and take up the full width, while 'inline' elements can start on the same line and only take up as much width as necessary.

How would you create a CSS rule that applies to multiple selectors?

You can create a CSS rule that applies to multiple selectors by separating each selector with a comma. For example, 'h1, h2, p { color: red; }' applies the same style to h1, h2 and p elements.

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The ideal back-end app developer

What you’re looking to see on the CSS engineer at this point.

At this point, the candidate should demonstrate a deep understanding of CSS, its interaction with HTML and JavaScript, and responsive design principles. They should show problem-solving skills through CSS coding challenges. Red flags include lack of detail in explanations, inability to solve problems or unfamiliarity with modern CSS frameworks or preprocessors.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with CSS.

What does the following CSS code do?

p {
 color: red;
}

This code snippet will make the text color of all paragraph elements ('p') red.

What does the following CSS code do?

.container {
 display: flex;
 flex-direction: column;
}

This code snippet applies a flex container layout to all elements with the class 'container'. The flex-direction property is set to column, which means the flex items will be laid out in a column, from top to bottom.

What does the following CSS code do?

#nav li {
 display: inline-block;
}

This code snippet will make all list items ('li') that are children of the element with the id 'nav' display as inline-block. This means that the list items will line up horizontally, but still retain block properties.

What does the following CSS code do?

h1 + p {
 margin-top: 0;
}

This code snippet will remove the top margin from any paragraph ('p') that directly follows a heading 1 ('h1') element. The '+' is an adjacent sibling combinator, which selects only the specified element that immediately follows the former specified element.

What does the following CSS code do?

div::after {
 content: '';
 display: table;
 clear: both;
}

This code snippet uses the ::after pseudo-element to clear floats after every 'div' element. The 'content' property is set to an empty string, the 'display' property is set to 'table', and the 'clear' property is set to 'both', which clears both left and right floats.

What does the following CSS code do?

@media (max-width: 600px) {
 .container {
 flex-direction: column;
 }
}

This code snippet uses a media query to change the flex-direction of elements with the class 'container' to column when the viewport is 600 pixels wide or less. This is often used to create a responsive layout that adjusts to different screen sizes.

Wrap-up questions

Final candidate for CSS role questions

The final few interview questions for a CSS candidate should typically focus on a combination of technical skills, personal goals, growth potential, team dynamics, and company culture.

What is the CSS cascade and how does it affect specificity?

The CSS cascade is the process of combining different stylesheets and resolving conflicts between different CSS rules and declarations when they apply to the same element. It affects specificity because it determines which rule applies if multiple rules have the same specificity.

How would you use CSS to create a layout with multiple columns?

You can use CSS to create a layout with multiple columns using techniques like CSS Grid or Flexbox. For example, with CSS Grid, you can use the grid-template-columns property to specify the number and widths of the columns.

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

Both 'em' and 'rem' are scalable units in CSS. 'em' is relative to the font-size of its closest parent, while 'rem' is only relative to the root (html) font-size.

How would you implement a CSS reset?

A CSS reset can be implemented by creating a CSS file that sets the margins, padding, and other properties of all elements to a consistent baseline value. This file should be linked in the HTML before any other CSS files.

What are CSS preprocessors and why are they useful?

CSS preprocessors, like Sass and LESS, allow developers to write CSS in a more programming-like way with features like variables, nesting, and mixins. They are useful because they can make CSS more maintainable and easier to write.

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CSS application related

Product Perfect's CSS development capabilities

Beyond hiring for your CSS engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in CSS projects, and can engage in multiple capacities.

CSS Consultive assessments

Custom CSS development projects

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