HTML Interview Questions

  • What does a doctype do?
  • How do you serve a page with content in multiple languages?
  • What kind of things must you be wary of when design or developing for multilingual sites?
  • What are data- attributes good for?
  • Consider HTML5 as an open web platform. What are the building blocks of HTML5?
  • Describe the difference between a cookie, sessionStorage and localStorage.
  • Describe the difference between <script>, <script async> and <script defer>.
  • Why is it generally a good idea to position CSS <link>s between <head></head> and JS <script>s just before </body>? Do you know any exceptions?
  • What is progressive rendering?
  • Why you would use a srcset attribute in an image tag? Explain the process the browser uses when evaluating the content of this attribute.
  • Have you used different HTML templating languages before?

CSS Interview Questions

  • What is CSS selector specificity and how does it work?
  • What's the difference between “resetting” and “normalizing” CSS? Which would you choose, and why?
  • Describe Floats and how they work.
  • Describe z-index and how stacking context is formed.
  • Describe BFC (Block Formatting Context) and how it works.
  • What are the various clearing techniques and which is appropriate for what context?
  • How would you approach fixing browser-specific styling issues?
  • How do you serve your pages for feature-constrained browsers? What techniques/processes do you use?
  • What are the different ways to visually hide content (and make it available only for screen readers)?
  • Have you ever used a grid system, and if so, what do you prefer?
  • Have you used or implemented media queries or mobile specific layouts/CSS?
  • Are you familiar with styling SVG?
  • Can you give an example of an @media property other than screen?
  • What are some of the "gotchas" for writing efficient CSS?
  • What are the advantages/disadvantages of using CSS preprocessors? Describe what you like and dislike about the CSS preprocessors you have used.
  • How would you implement a web design comp that uses non-standard fonts?
  • Explain how a browser determines what elements match a CSS selector.
  • Describe pseudo-elements and discuss what they are used for.
  • Explain your understanding of the box model and how you would tell the browser in CSS to render your layout in different box models.
  • What does * { box-sizing: border-box; } do? What are its advantages?
  • What is the CSS display property and can you give a few examples of its use?
  • What’s the difference between inline and inline-block?
  • What’s the difference between the nth-of-type() and nth-child() selectors?
  • What's the difference between a relative, fixed, absolute and statically positioned element?
  • What existing CSS frameworks have you used locally, or in production? How would you change/improve them?
  • Have you used CSS Grid?
  • Can you explain the difference between coding a web site to be responsive versus using a mobile-first strategy?
  • Have you ever worked with retina graphics? If so, when and what techniques did you use?
  • Is there any reason you'd want to use translate() instead of absolute positioning, or vice-versa? And why?