AceStack AI

Knowledge Check

Trapped z-index

Why can z-index: 9999 still appear below a sibling overlay?

What this task practices

Trapped z-index is a knowledge check interview exercise that trains prompt interpretation, explicit assumptions, a concrete response, and a clear explanation of tradeoffs. The catalog marks it as hard difficulty. It focuses on Frontend Foundations, CSS Positioning Stacking. The signed-in workspace provides the tools for the round and evaluates the attempt against task-specific criteria. Reference solutions, hidden checks, evaluator instructions, and candidate work remain private.

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