Unveiling the Cause of Stacking Order Alterations in Webkit Filters

In web development, maintaining the desired stacking order of elements is often crucial. However, certain actions can disrupt this order, leaving developers bewildered. One such instance arises when applying a Webkit filter to an image.

Upon hovering over an image with a Webkit filter applied, the stacking order can inexplicably change. This puzzling phenomenon has been the topic of much speculation and frustration.

Thankfully, the answer lies in the realm of CSS specifications. The Webkit Filter property, when assigned a value other than none, establishes a stacking context. This concept, defined in the CSS spec, dictates that the element in question becomes a container for other elements and creates a separate layer in the visual hierarchy.

As per the spec:

"A computed value of other than none results in the creation of a stacking context the same way that CSS opacity does."

This means that applying a Webkit filter to an image creates a new stacking context, which overrides the existing stacking order and places the filtered image above other elements.

Understanding this underlying mechanism empowers developers to resolve stacking order issues without resorting to z-indexing, which can potentially disrupt other elements on the page.