CSS Performance Optimization Quiz
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Question 1/15
Which practice can help avoid text layout shifts during page loading?
Select your answer
Question 2/15
Why is it advisable to use only
@supports
rules for checking variable CSS features?
Select your answer
Question 3/15
Why is it important to specify the size for images used in CSS backgrounds for performance optimization?
Select your answer
Question 4/15
Why should you avoid using
*
selectors in performance-critical CSS?
Select your answer
Question 5/15
Which performance issue may arise from incorrect cascading of CSS styles in a large application?
Select your answer
Question 6/15
How does critical CSS enhance the user experience specifically for performance?
Select your answer
Question 7/15
Which CSS technique might be used to ensure layout transition animations are smooth with minimal repaint and reflow?
Select your answer
Question 8/15
What is a potential downside of using CSS custom properties (
var(--my-variable-name)
) on very high-dynamic elements for performance?
Select your answer
Question 9/15
What issues can arise if CSS is not effectively minified before deployment?
Select your answer
Question 10/15
Which part of the CSSOM (CSS Object Model) might lead to layout thrashing during interactive operations like animations?
Select your answer
Question 11/15
Which strategy is recommended for minimizing unused CSS to improve performance?
Select your answer
Question 12/15
Which of the following CSS rules will most likely lead to a performance bottleneck due to inefficient selector usage?
Select your answer
Question 13/15
How can you optimize CSS animations for better performance in modern browsers?
Select your answer
Question 14/15
Which CSS feature, if used incorrectly, can lead to unnecessary repaints and reflows, negatively impacting performance?
Select your answer
Question 15/15
How does using CSS pre-processing tools like SASS or LESS improve CSS performance?
Select your answer
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Your Answers
Question 1/15
π Your
answer was correct
π Your
answer was incorrect
Which practice can help avoid text layout shifts during page loading?
Available answers
Using
font-display: optional;
allows the browser to swap fonts without waiting, preventing layout shifts or flashes of invisible text while prioritizing initial content display.
Question 2/15
π Your
answer was correct
π Your
answer was incorrect
Why is it advisable to use only
@supports
rules for checking variable CSS features?
Available answers
@supports
rules allow conditional application of CSS depending on browser support for certain features, helping prevent unsupported rules from processing, making CSS more stable and performant.
Question 3/15
π Your
answer was correct
π Your
answer was incorrect
Why is it important to specify the size for images used in CSS backgrounds for performance optimization?
Available answers
Specifying image sizes allows the page layout to allocate space for images before they load, preventing reflows and unnecessary layout recalculations.
Question 4/15
π Your
answer was correct
π Your
answer was incorrect
Why should you avoid using <pre><code>*</code></pre> selectors in performance-critical CSS?
Available answers
Using the universal selector
*
forces the browser to consider all DOM elements, leading to slower style recalculations, hence decreasing performance.
Question 5/15
π Your
answer was correct
π Your
answer was incorrect
Which performance issue may arise from incorrect cascading of CSS styles in a large application?
Available answers
Incorrect cascading in CSS can lead to excessive specificity, meaning changes to styles might require significant recalculation and reapplication of styles impacting performance, especially in large applications.
Question 6/15
π Your
answer was correct
π Your
answer was incorrect
How does critical CSS enhance the user experience specifically for performance?
Available answers
Critical CSS involves inlining the necessary CSS for the content above the fold into the HTML to ensure it renders immediately, without waiting for external resources to load, improving user-perceived load times.
Question 7/15
π Your
answer was correct
π Your
answer was incorrect
Which CSS technique might be used to ensure layout transition animations are smooth with minimal repaint and reflow?
Available answers
Using
transform
and opacity
properties ensures that animations are offloaded to the GPU, minimizing the need for CPU-intensive style recalculations, repaints, and reflows.
Question 8/15
π Your
answer was correct
π Your
answer was incorrect
What is a potential downside of using CSS custom properties (
var(--my-variable-name)
) on very high-dynamic elements for performance?
Available answers
CSS custom properties are resolved at runtime, meaning changes to them can cause recalculation that, if not managed carefully, can impact performance when applied to many dynamic elements.
Question 9/15
π Your
answer was correct
π Your
answer was incorrect
What issues can arise if CSS is not effectively minified before deployment?
Available answers
Not minifying CSS leads to larger file sizes, which in turn means longer download times and slower initial page loads, thus impacting the overall performance and user experience.
Question 10/15
π Your
answer was correct
π Your
answer was incorrect
Which part of the CSSOM (CSS Object Model) might lead to layout thrashing during interactive operations like animations?
Available answers
The style resolution during animations can cause layout thrashing if style reads and writes are not batched correlatively, as frequent recalculations can lead to dropped frames and jank.
Question 11/15
π Your
answer was correct
π Your
answer was incorrect
Which strategy is recommended for minimizing unused CSS to improve performance?
Available answers
Tools like PurgeCSS analyze your HTML, JavaScript, and CSS to determine which styles are used and which can be safely removed, reducing the file size and improving load times.
Question 12/15
π Your
answer was correct
π Your
answer was incorrect
Which of the following CSS rules will most likely lead to a performance bottleneck due to inefficient selector usage?
Available answers
The selector
div + p :nth-child(3)
uses a pseudo-class (:nth-child) and a sibling selector (+), which can be computationally expensive because the browser may need to examine a significant portion of the DOM to find matching elements.
Question 13/15
π Your
answer was correct
π Your
answer was incorrect
How can you optimize CSS animations for better performance in modern browsers?
Available answers
Using properties like
transform
and opacity
leverages GPU acceleration, improving animation performance compared to other properties that may trigger reflows or repaints.
Question 14/15
π Your
answer was correct
π Your
answer was incorrect
Which CSS feature, if used incorrectly, can lead to unnecessary repaints and reflows, negatively impacting performance?
Available answers
When
position: absolute
is used incorrectly or excessively, it can increase the complexity of calculating the element's position, potentially leading to costly reflows.
Question 15/15
π Your
answer was correct
π Your
answer was incorrect
How does using CSS pre-processing tools like SASS or LESS improve CSS performance?
Available answers
CSS preprocessors like SASS and LESS allow for variable use, nesting, and includes that can reduce redundant CSS, leading to smaller file sizes before they reach the client.