Performance considerations in CSS - Cheat Sheet & Quick Revision

Recall & Review

beginner

Why should you minimize the use of complex CSS selectors?

Complex selectors take longer for the browser to match, which can slow down page rendering. Using simple selectors helps improve performance.

beginner

What is the benefit of using CSS shorthand properties?

Shorthand properties reduce the size of CSS files, which means faster downloads and quicker rendering by the browser.

beginner

How does reducing the number of CSS files improve performance?

Fewer CSS files mean fewer HTTP requests, which reduces loading time and speeds up page display.

intermediate

Why is it important to avoid using @import in CSS for performance?

@import causes additional HTTP requests and delays CSS loading, slowing down page rendering.

intermediate

What role does CSS specificity play in performance?

High specificity selectors can make CSS harder to maintain and may cause the browser to do more work to apply styles, affecting performance.

Which CSS selector is generally fastest for the browser to match?

A Attribute selector (e.g., [type='text'])

B Type selector (e.g., div)

C Descendant selector (e.g., div p)

D Universal selector (*)

Type selectors are simple and fast because the browser can quickly match elements by their tag name.

What is a good practice to reduce CSS file size and improve performance?

A Use CSS shorthand properties

B Use inline styles everywhere

C Use many separate CSS files

D Use !important on all rules

CSS shorthand properties reduce file size by combining multiple properties into one line.

Why should you avoid using @import in CSS files?

A It increases HTTP requests and delays loading

B It makes CSS invalid

C It disables caching

D It causes CSS to be ignored

@import adds extra HTTP requests and delays CSS loading, hurting performance.

How does reducing the number of CSS selectors improve performance?

A It disables CSS animations

B It increases CSS specificity

C It makes CSS files larger

D Browser matches fewer selectors, speeding up rendering

Fewer selectors mean less work for the browser to find matching elements.

Which practice helps improve CSS performance on mobile devices?

A Using large background images without optimization

B Using many nested selectors

C Minimizing CSS and using media queries

D Using inline styles for all elements

Minimizing CSS and using media queries helps load only necessary styles, improving mobile performance.

Explain three ways to improve CSS performance on a website.

Think about how browsers read and apply CSS.

Describe why reducing HTTP requests matters for CSS performance.

Consider how the browser fetches files from the server.