Does Z-Index Stacking Order Depend on Parent Element\'s Z-Index?

Is the Z-Index Measurement of an Element Absolute or Relative?

The positioning of elements on a web page is determined by their z-index style. However, concerns have arisen regarding the absolute nature of their stack order or its relativity to their parent elements. This article aims to address these concerns within the context of browser implementation disparities.

Beginning with the established standards, z-index is indeed a relative property, signifying the stack order of an element relative to its immediate parent. This implies that an element's stacking behavior is influenced solely by its parent's z-index.

To illustrate this concept, consider the following scenario:

<code class="html"><div style="z-index:-100">
    <div id="dHello" style="z-index:200">Hello World</div>
</div>

<div id="dDomination" style="z-index:100">I Dominate!</div></code>

Based on the standards, #dHello should appear in front of #dDomination, as its z-index of 200 is higher than #dDomination's 100, despite its parent's negative z-index (-100).

However, browser implementations have introduced inconsistencies. In some browsers, the parent element's z-index is considered, even though it contradicts the official definition. Thus, #dDomination may appear in front of #dHello in such cases.

Variation in Browser Implementation:

• Internet Explorer: Previous versions disregarded the parent's z-index, while newer versions consider it.
• Firefox: Always considers the parent's z-index.
• Chrome and Safari: Typically follow the relative z-index model, but certain scenarios can lead to the parent's z-index being considered.

Conclusion:

Z-index is essentially a relative property. However, browser implementations may introduce variances in its behavior. For consistent results, it is recommended to use the relative model as described in the CSS specifications and be aware of possible browser-specific exceptions.

The above is the detailed content of Does Z-Index Stacking Order Depend on Parent Element\'s Z-Index?. For more information, please follow other related articles on the PHP Chinese website!