Скачать или смотреть Understanding z-index Behavior in Folder Tabs: Why Does z-index: -1 Not Work?

Explore why `z-index: -1` fails in your folder tabs and learn how to resolve the issue by adjusting the CSS properties.
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This video is based on the question https://stackoverflow.com/q/67900217/ asked by the user 'salar kazazi' ( https://stackoverflow.com/u/8557645/ ) and on the answer https://stackoverflow.com/a/67900836/ provided by the user 'Martin' ( https://stackoverflow.com/u/5541550/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

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Understanding z-index Behavior in Folder Tabs: Why Does z-index: -1 Not Work?

When developing interactive elements in web design, such as folder tabs, you may encounter unexpected behavior with CSS properties like z-index. This post aims to clarify why you might experience issues with z-index: -1 in your folder tab implementation and provide a solution to fix the problem.

The Problem: z-index Issues in Folder Tabs

In your current implementation, you are trying to achieve a visual effect where the clicked tab should stand out and appear above other tabs. Your CSS code attempts to use z-index to achieve this:

[[See Video to Reveal this Text or Code Snippet]]

The intent is clear: when a tab is clicked, it should elevate above the others. However, you discovered that setting z-index: -1 causes the clicked tab to not behave as expected and requested clarification on why this is the case.

Why z-index: -1 Causes Problems

Understanding Context Stacking:
z-index only works on positioned elements (position: relative, position: absolute, or position: fixed). By using z-index: -1, your tab labels may not stack in the intended order. When an element is given a negative z-index, it will be layered behind the parent element or other sibling elements with no specific stacking order.

The Role of Parent Elements:
In this case, the parent container needs to have a z-index value set too. If not, the labels can be pushed behind the root element of your page, causing the clicked tab not to be displayed as expected. Thus, z-index values only work when the surrounding context supports that layering.

Solution: Correcting the CSS for Proper z-index Behavior

To resolve this issue, we can use a slightly different approach with your CSS. Here are the steps you can take:

1. Adjust Parent z-index

Add a z-index: 0; to the parent of the tabs to ensure the stacking context is correctly set up.

[[See Video to Reveal this Text or Code Snippet]]

2. Change Visibility Method of Radio Inputs

Instead of using display: none; for your radio inputs, which entirely removes them from the layout flow, switch to using opacity and positioning. This way, they remain part of the layout and maintain their z-index hierarchy.

[[See Video to Reveal this Text or Code Snippet]]

3. Simplified CSS Implementation

Here’s a refined version of your CSS:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

By adjusting both the parent element's z-index and the method for handling visibility of radio input elements, you can successfully create a clean and efficient tab system that registers user interaction as expected. Using z-index: auto; tends to play better due to its relationship with the hierarchy of the layout context, making it a safer option in cases where stacking order can be ambiguous. Happy coding!