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Z-Index Visualizer

Visualize and manage z-index stacking contexts.

Z-Index Layers

Stack Visualization

dropdownz:10

stickyz:20

modal-backdropz:30

modalz:40

popoverz:50

tooltipz:60

Layer Order (Top to Bottom)

tooltip60

popover50

modal40

modal-backdrop30

sticky20

dropdown10

Generated CSS

/* Z-Index Scale */
:root {
  --z-dropdown: 10;
  --z-sticky: 20;
  --z-modal-backdrop: 30;
  --z-modal: 40;
  --z-popover: 50;
  --z-tooltip: 60;
}

/* Usage */
.dropdown { z-index: var(--z-dropdown); }
.modal { z-index: var(--z-modal); }
.tooltip { z-index: var(--z-tooltip); }

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What is this

What is the CSS Z-Index Visualizer?

Visualize stacking contexts and z-index layers. Understand why elements overlap incorrectly and fix layering issues.

Everything runs locally in your browser. Adjust the controls above, preview instantly, and copy clean, production-ready CSS — no account, no upload.

How to use

Using the CSS Z-Index Visualizer

Everything lives in the panel at the top of this page. There is nothing to install — it all runs right here in your browser.

Add layers

Enter element names and z-index values to visualize their stacking order.

View the stacking context

The visualizer shows which elements form new stacking contexts and isolate their children.

Identify conflicts

Compare the visual layer order against expected overlapping to identify why an element appears above or below its intended position.

The output

What the generated code looks like

Clean, production-ready CSS — no vendor bloat, no unnecessary declarations.

stacking.css

/* New stacking context is created by: */
.modal-overlay {
  position: fixed;
  z-index: 1000;
}

.modal {
  position: relative;
  z-index: 1001; /* must be higher than overlay within same stacking context */
}

/* Parent creates a new stacking context — child z-index is isolated */
.isolated {
  transform: translateZ(0); /* creates new stacking context */
  z-index: 1;
}

.isolated .child {
  z-index: 9999; /* only competes within .isolated, not the entire page */
}

Any element with transform, opacity < 1, filter, will-change, or isolation: isolate creates a new stacking context. Children z-index values only compete within that context, not globally.

Common mistakes & fixes

Common mistakes & how to fix them

A few habits trip people up. Here is what to watch for — and the exact fix.

Setting z-index without position

z-index has no effect on elements with position: static (the default). The element stays in normal flow regardless of the z-index value.

Fix: Add position: relative, absolute, fixed, or sticky alongside any z-index declaration.

Fighting z-index with large values (9999, 999999)

Incrementing z-index to large numbers is a symptom of not understanding stacking contexts. It creates maintenance debt and eventually fails.

Fix: Map your layering semantics to a scale: 100 for dropdowns, 200 for sticky headers, 300 for modals, 400 for toasts. Identify which elements create stacking contexts and scope z-index within them.

Pro tips

Pro tips for better results

★

Use isolation: isolate to create a stacking context without side effects

isolation: isolate creates a new stacking context without the side effects of transform or opacity. Use it on component wrappers to prevent z-index bleed between components.

FAQ

Frequently asked questions

The modal is inside a stacking context created by an ancestor with transform, opacity, filter, or will-change. Its z-index only competes within that ancestor. Move the modal to the top of the DOM (document.body) to escape the stacking context.

Positioned elements (relative, absolute, fixed, sticky) with no z-index set have z-index: auto, which means they participate in the stacking context of their ancestor. Within the same stacking context, later elements in the DOM appear above earlier elements at the same z-index level.