CSS Performance Optimization Quiz
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Question 1/15
Which CSS feature, if used incorrectly, can lead to unnecessary repaints and reflows, negatively impacting performance?
Select your answer
Question 2/15
Why should you avoid using
*
selectors in performance-critical CSS?
Select your answer
Question 3/15
What technique prevents layout recalculations when adding a large number of CSS-modified elements to the DOM?
Select your answer
Question 4/15
What optimization benefit does using
font-display: swap;
provide for web fonts in CSS?
Select your answer
Question 5/15
How does critical CSS enhance the user experience specifically for performance?
Select your answer
Question 6/15
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 7/15
How does deferring or async loading of CSS affect page performance metrics like FCP (First Contentful Paint)?
Select your answer
Question 8/15
How can you optimize CSS animations for better performance in modern browsers?
Select your answer
Question 9/15
What issues can arise if CSS is not effectively minified before deployment?
Select your answer
Question 10/15
Why is it advisable to use only
@supports
rules for checking variable CSS features?
Select your answer
Question 11/15
Which part of the CSSOM (CSS Object Model) might lead to layout thrashing during interactive operations like animations?
Select your answer
Question 12/15
Which performance issue may arise from incorrect cascading of CSS styles in a large application?
Select your answer
Question 13/15
What is a key downside of placing too much CSS inline in HTML for performance purposes?
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Question 14/15
What is the main advantage of using CSS Grid over CSS Flexbox for performance optimization?
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Question 15/15
Which technique allows efficient use of media queries for optimizing CSS performance?
Select your answer
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Your Answers
Question 1/15
😊 Your
answer was correct
🙁 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 2/15
😊 Your
answer was correct
🙁 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 3/15
😊 Your
answer was correct
🙁 Your
answer was incorrect
What technique prevents layout recalculations when adding a large number of CSS-modified elements to the DOM?
Available answers
Document fragments allow for elements to be inserted into the DOM in bulk, reducing the number of reflows and layout recalculations needed, thus providing better performance.
Question 4/15
😊 Your
answer was correct
🙁 Your
answer was incorrect
What optimization benefit does using
font-display: swap;
provide for web fonts in CSS?
Available answers
The
font-display: swap;
property ensures text is displayed immediately using a fallback font until the custom font can be loaded, preventing invisible text (flash of invisible text -- FOIT).
Question 5/15
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answer was correct
🙁 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 6/15
😊 Your
answer was correct
🙁 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 7/15
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answer was correct
🙁 Your
answer was incorrect
How does deferring or async loading of CSS affect page performance metrics like FCP (First Contentful Paint)?
Available answers
By deferring the load of non-critical CSS, the browser can prioritize rendering the viewport content, thus improving metrics such as First Contentful Paint (FCP).
Question 8/15
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answer was correct
🙁 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 9/15
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answer was correct
🙁 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
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answer was correct
🙁 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 11/15
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answer was correct
🙁 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 12/15
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answer was correct
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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 13/15
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answer was correct
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answer was incorrect
What is a key downside of placing too much CSS inline in HTML for performance purposes?
Available answers
While inline CSS can improve the initial page load, it prevents styles from being cached across requests, leading to longer load times for subsequent page views.
Question 14/15
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answer was correct
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answer was incorrect
What is the main advantage of using CSS Grid over CSS Flexbox for performance optimization?
Available answers
CSS Grid allows defining both rows and columns in a layout, often reducing the number of complex nesting and code needed, which can lessen layout recalculations compared to Flexbox used in certain scenarios.
Question 15/15
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answer was correct
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answer was incorrect
Which technique allows efficient use of media queries for optimizing CSS performance?
Available answers
A mobile-first approach involves applying base styles that are progressively enhanced using media queries as screen size or device capabilities increase, ensuring only necessary styles are applied initially, reducing overhead.