Why Does `clip-path` Change Element Stacking Order?

Why Does Clip-Path Affect Stacking Order?

When applied to an element, clip-path acts similarly to CSS opacity with a value less than 1. According to the CSS specification, such properties create a stacking context, which influences the painting order of elements.

Stacking Context Formation

A stacking context is a two-dimensional plane that contains child elements arranged in a specific order. Once a stacking context is established, elements within it are rendered in a front-to-back or back-to-front sequence.

Painting Order with Clip-Path

According to the painting order, all positioned or opacity descendants (with opacity less than 1) create new stacking contexts atomically. This means they form their own stacking context and become isolated from the rest of the document.

In our example, the element with clip-path creates a stacking context at the 8th step of the painting process. However, the image in the code is not positioned and is therefore considered an in-flow non-positioned element. This means it is painted at a later step (4) in the painting process.

Position:relative and Stacking Order

By adding position:relative to the image, we essentially force it into forming its own stacking context. This ensures that the image is painted at the 8th step, along with the header with clip-path. Now, the image will be positioned above the header due to its tree order.

Conclusion

The affect of clip-path on the stacking order of elements later in the DOM arises from its creation of a stacking context atomically. Elements within this context are painted before other elements that are considered in-flow non-positioned.

The above is the detailed content of Why Does `clip-path` Change Element Stacking Order?. For more information, please follow other related articles on the PHP Chinese website!