Answer
A stacking context is an independent three-dimensional painting context. • Descendants are stacked together inside their context. • The completed context is then treated as one unit in its parent context. • A descendant z-index cannot place content outside its ancestor stacking context.
💡 Simple Example
.modal {
position: fixed;
z-index: 10;
isolation: isolate;
}
⚡ Quick Revision
A stacking context groups painting order so descendants cannot escape it.