Z-Index

Definitions

1. A CSS property controlling the stacking order of overlapping positioned elements. Higher values appear in front. Notoriously confusing because z-index only works within stacking contexts — a z-index: 9999 element inside a stacking context with z-index: 1 will still appear behind z-index: 2 in a sibling context.

   In plain English: The CSS property that controls which elements appear in front of others when they overlap — and the source of endless frustration.

   Example: "Setting z-index: 99999 didn't fix the dropdown appearing behind the modal — it's a stacking context issue, not a number issue."

Related Terms

• Grid
• Selector
• CSS Custom Properties
• CSS Grid
• Flexbox
• Container Query
• BEM
• Masonry Layout
• Scroll Snap
• CSS Layout