Key Points
- The CSS
content-visibilityproperty likely improves web page performance by controlling when content is rendered. - It seems to help by skipping rendering of off-screen content, making pages load faster.
- Research suggests it has values like
visible,hidden, andauto, each affecting how content appears.
What is the content-visibility Property?
The content-visibility property in CSS is a tool that decides whether a web page element’s content should be shown right away or later. It’s like telling your browser, “Don’t bother showing this part yet if it’s not visible to the user.”
How Does It Work?
This property can skip rendering work, like laying out and painting, for content that’s not currently visible, such as parts of a long page you haven’t scrolled to yet. This can make your page load faster, especially on slower devices.
Common Uses
It’s often used for long articles or websites with lots of images, where you want the visible part to load quickly while the rest waits until needed.
Survey Note: Detailed Analysis of the CSS content-visibility Property
The CSS content-visibility property is a relatively recent addition to the CSS specification, designed to enhance web page rendering performance by optimizing how browsers handle the rendering of content. This section provides a comprehensive overview, drawing from authoritative sources and detailed technical insights, to ensure a thorough understanding for developers and technical audiences.
Definition and Purpose
The content-visibility property, as defined by the MDN Web Docs, controls whether an element renders its contents at all, enforcing a strong set of containments that allow user agents (browsers) to potentially omit large swathes of layout and rendering work until the content becomes necessary. Its primary purpose is to improve rendering performance, particularly during initial page loads, by deferring the rendering of off-screen or irrelevant content. This is especially beneficial for long pages or content-heavy websites, where rendering all content at once can slow down the user experience.
The property enables browsers to skip rendering work, including layout and painting, for elements that are not currently visible to the user. This deferral can significantly reduce the initial load time, making pages feel faster and more responsive, particularly on devices with limited processing power or slower network connections.
Values and Behavior
The content-visibility property accepts three main values, each with distinct behaviors:
- visible: This is the default value, where the element’s contents are rendered normally, with no performance optimizations applied. The browser processes the content as it would without the property, laying out and painting it as part of the initial render.
- hidden: This value skips the rendering of the element’s contents, making them inaccessible to user-agent features, similar to applying
display: none. However, unlikedisplay: none, the element still occupies space in the layout, and its rendering state is preserved for potential future rendering. - auto: This value turns on layout, style, and paint containment, allowing the browser to decide whether to render the contents based on their relevance to the user, such as whether they are near or in the viewport. Off-screen content with
content-visibility: autoremains in the document object model (DOM) and accessibility tree, ensuring accessibility is not compromised. This is particularly useful for lazy loading scenarios, where content is rendered only when needed.
Additionally, global CSS values such as inherit, initial, revert, revert-layer, and unset can be applied, though they are less commonly used in practice for this property.
Performance Implications
The performance benefits of content-visibility are significant, especially for websites with complex layouts or large amounts of content. By deferring the rendering of off-screen elements, the browser can allocate more resources to rendering the visible portion of the page, improving metrics like Interaction to Next Paint (INP) and First Contentful Paint (FCP). This is particularly evident in scenarios like travel blogs with multiple stories, where each story’s content can be deferred until the user scrolls to it, as noted in technical articles from sources like Xenonstack.
The property works in conjunction with the CSS Containment specification, which isolates elements to prevent unnecessary reflows and repaints. This containment ensures that changes to one part of the page do not affect others, further enhancing performance.
Accessibility Considerations
One important aspect is the property’s impact on accessibility. When using content-visibility: auto, off-screen content remains in the DOM and accessibility tree, ensuring that screen readers and other assistive technologies can still access it. However, for elements that should be excluded from the accessibility tree (e.g., decorative content), developers may need to manually add aria-hidden="true" to prevent unexpected behavior, as highlighted in articles from LogRocket Blog. This ensures that performance optimizations do not compromise user experience for those relying on assistive technologies.
Event Handling
A related feature is the contentvisibilityautostatechange event, which fires on elements with content-visibility: auto when their rendering work starts or stops being skipped. This event provides a convenient way for developers to manage additional rendering processes, such as drawing on a <canvas> element, only when the content becomes relevant. This can conserve processing power and further optimize performance, as detailed in the MDN documentation.
Browser Support and Adoption
Browser support for content-visibility is robust as of May 31, 2025, with widespread adoption across modern browsers. The following table summarizes the support across major browsers, based on data from the “Can I use” database:
| Browser | Supported Versions | Not Supported Versions | Disabled by Default Versions | Notes/URLs |
|---|---|---|---|---|
| Chrome | 85-140 | 4-84 | – | – |
| Edge | 85-136 | 12-84 | – | – |
| Safari | 18.0-18.5, TP | 3.1-17.6 | – | WebKit support bug |
| Firefox | 125-142 | 2-108 | 109-124 | Firefox support bug |
| Opera | 71-117 | 9-70 | – | – |
| IE | – | 5.5-11 | – | – |
| Chrome for Android | 136 | – | – | – |
| Safari on iOS | 18.0-18.5 | 3.2-17.7 | – | – |
| Samsung Internet | 14.0-27 | 4-13.0 | – | – |
| Opera Mini | – | all | – | – |
| Opera Mobile | 80 | 10-12.1 | – | – |
| UC Browser for Android | 15.5 | – | – | – |
| Android Browser | 136 | 2.1-4.4.4 | – | – |
| Firefox for Android | 137 | – | – | – |
| QQ Browser | – | 14.9 | – | – |
| Baidu Browser | 13.52 | – | – | – |
| KaiOS Browser | – | 2.5, 3 | – | – |
Given the current date, the property is fully supported across all modern browsers, with no significant gaps in coverage. This aligns with its inclusion in Baseline 2024, as noted in articles from 12 Days of Web, indicating its readiness for production use.
Practical Examples and Use Cases
Practical use cases include lazy loading of content in long-scrolling pages, such as blog posts, e-commerce product listings, or galleries. For instance, a travel blog with multiple stories can apply content-visibility: auto to each story section, ensuring that only the visible story is rendered initially, with others loaded as the user scrolls. This approach is detailed in articles from web.dev, which demonstrate performance improvements using the auto keyword.
Another example is hiding decorative elements that are not immediately relevant, using content-visibility: hidden, while ensuring the layout space is preserved. This is different from display: none, as noted in CSS-Tricks, where content-visibility applies to all content, including text nodes and pseudo-content, not just child elements.
Comparison with Related Properties
It’s worth comparing content-visibility with related CSS properties like visibility and display. The visibility property, as per MDN, controls whether an element is visible but does not affect layout (e.g., visibility: hidden hides the element but keeps its space), while display: none removes the element entirely from the layout. In contrast, content-visibility focuses on rendering performance, with hidden and auto offering different levels of control over when and how content is rendered.
Challenges and Considerations
While content-visibility offers significant performance benefits, there are challenges to consider. For instance, developers must ensure that changes to the HTML structure do not inadvertently break containment conditions, which could undo performance gains, as noted in LogRocket Blog. Additionally, awareness of the property is still growing, with the State of CSS 2023 survey indicating it as a featured item, suggesting that adoption may vary across teams.
Conclusion
The CSS content-visibility property is a powerful tool for optimizing web page rendering performance, particularly for content-heavy websites. Its ability to defer rendering of off-screen content, combined with strong browser support as of May 31, 2025, makes it a valuable addition to the developer’s toolkit. By understanding its values, accessibility implications, and practical use cases, developers can leverage this property to create faster, more responsive web experiences.