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Z-Index Visualizer

Visualize CSS stacking context and z-index layering for HTML elements online for free. Add layers, set their z-index values and position properties, toggle stacking contexts, and see exactly how elements stack on top of each other in a live diagram. Debug z-index conflicts and understand stacking contexts instantly. No signup required.

Z-Index Visualizer

Add layers, set their z-index, position, and opacity. The visualization shows how elements stack on top of each other. Layers with isolation: isolate create new stacking contexts. All processing runs locally in your browser.

Stacking Visualization

Higher z-index = on top
Base Card
z: 1
Dropdown Menu
z: 100
Modal Overlay
z: 1000
Tooltip
z: 9999
Stacking Order (bottom → top)
1
Base Cardz: 1relative
2
Dropdown Menuz: 100absolutectx
3
Modal Overlayz: 1000fixedctx
4
Tooltipz: 9999absolute

Layers(4 total)

Generated CSS

.base-card {
  position: relative;
  z-index: 1;
  opacity: 0.85;
}

.dropdown-menu {
  position: absolute;
  z-index: 100;
  opacity: 0.9;
  /* Creates new stacking context */
  isolation: isolate;
}

.modal-overlay {
  position: fixed;
  z-index: 1000;
  opacity: 0.8;
  /* Creates new stacking context */
  isolation: isolate;
}

.tooltip {
  position: absolute;
  z-index: 9999;
  opacity: 0.95;
}
How to read the visualization
White dot on layer: Layer creates a new stacking context (isolation: isolate)
ctx badge: Layer has its own stacking context — child z-indexes are scoped to it
z-index only works on positioned elements (not static)
Stacking context is created by: position + z-index, opacity < 1, transform, filter, isolation

Why Use Our Z-Index Visualizer?

Understand CSS stacking order and debug z-index issues visually

Live Z-Index Stacking Visualization

Our z-index visualizer renders a live stacking diagram that updates instantly as you add, edit, or reorder layers. See exactly how elements stack on top of each other based on their z-index values and position properties.

Stacking Context Detection

Our z-index visualizer highlights layers that create new stacking contexts. Toggle the "New stacking context" checkbox to see how isolation scopes child z-index values — the most common source of z-index bugs.

Secure Z-Index Visualizer Online

All z-index visualization runs entirely in your browser — no data is sent to any server. Your layer configurations never leave your device. Use our z-index visualizer safely for client projects and proprietary UI designs.

Z-Index Visualizer — No Installation, 100% Free

Use our z-index visualizer directly in any browser with no downloads, no account, and no ads. Generates production-ready CSS with z-index and position declarations for all your layers — completely free forever.

Common Use Cases for Z-Index Visualizer

From debugging to design systems — z-index visualization for every workflow

Debugging Z-Index Conflicts

Developers use our z-index visualizer to debug UI elements that appear behind other elements unexpectedly. Add your layers, set their z-index values, and instantly see why one element is hidden behind another.

Understanding Stacking Contexts

Use our z-index visualizer to understand how stacking contexts scope z-index values. The "New stacking context" toggle shows how a parent with opacity < 1 or transform can trap child elements regardless of their z-index.

Modal & Overlay Architecture

Frontend developers use our z-index visualizer to plan the z-index hierarchy for modals, overlays, tooltips, and dropdowns. Visualize the full stack before writing a single line of CSS.

Design System Z-Index Tokens

Design system teams use our z-index visualizer to define and document z-index tokens. Visualize the complete stacking hierarchy — base, dropdown, sticky, modal, toast, tooltip — and export the CSS.

Teaching CSS Stacking

Educators and developers learning CSS use our z-index visualizer to understand how z-index, position, and stacking contexts interact. The live visualization makes abstract concepts immediately tangible.

Component Library Planning

Use our z-index visualizer to plan the stacking order for component libraries. Ensure that tooltips always appear above modals, and that sticky headers never overlap dropdown menus.

Understanding CSS Z-Index and Stacking Contexts

How z-index works and why stacking contexts are the root cause of most z-index bugs

What is a Z-Index Visualizer?

A z-index visualizer is a tool that renders a visual diagram of how HTML elements stack on top of each other based on their z-index and position CSS properties. In CSS, elements with higher z-index values appear in front of elements with lower values — but only when they share the same stacking context. Our z-index visualizer lets you add layers, set their z-index and position values, toggle stacking contexts, and see the exact stacking order in a live diagram — making it easy to understand and debug complex layering issues.

How Our Z-Index Visualizer Works

  1. Add Your Layers: Click Add Layer to create a new element. Set its name, z-index value, CSS position property, color, and opacity. Toggle visibility to show or hide layers in the visualization without deleting them.
  2. Visualize the Stack:The diagram updates instantly as you edit any layer. Layers are shown stacked from bottom (lowest z-index) to top (highest z-index). Layers with a new stacking context are marked with a white dot and a “ctx” badge in the order list.
  3. Copy the CSS: The generated CSS panel shows the complete z-index and position declarations for all your layers. Copy it with one click and paste it into your stylesheet.

Key Z-Index Concepts

  • z-index only works on positioned elements: Setting z-index on an element with position: static (the default) has no effect. You must use relative, absolute, fixed, or sticky.
  • Stacking contexts scope z-index: A stacking context is a self-contained layer group. Z-index values inside a stacking context only compete with other elements inside the same context — not with elements outside it. This is why a z-index of 9999 inside a modal can still appear behind a tooltip outside the modal.
  • What creates a stacking context: The root element, any element with position and a non-auto z-index, opacity < 1, transform, filter, isolation: isolate, and several other CSS properties.
  • The most common z-index bug: A parent element with opacity < 1 or transform creates a new stacking context, trapping all child elements inside it — no matter how high their z-index values are.

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Frequently Asked Questions About Z-Index Visualizer

Common questions about CSS z-index, stacking contexts, and how our visualizer works

A z-index visualizer renders a live diagram of how HTML elements stack on top of each other based on their z-index and position CSS properties. Our z-index visualizer lets you add layers, set their z-index values, toggle stacking contexts, and see the exact stacking order instantly in your browser.

The most common reasons z-index does not work: 1) The element has position: static (z-index only works on positioned elements). 2) A parent element creates a new stacking context (due to opacity < 1, transform, filter, or isolation: isolate), trapping the element inside it regardless of its z-index value.

A stacking context is a self-contained layer group in CSS. Z-index values inside a stacking context only compete with other elements inside the same context. This is why a z-index of 9999 inside a modal can still appear behind a tooltip outside the modal — they are in different stacking contexts.

Yes. All z-index visualization runs entirely in your browser — your layer configurations never leave your device and are never sent to any server.

Yes, our z-index visualizer is 100% free with no signup, no account, no usage limits, and no advertisements.

A new stacking context is created by: position with a non-auto z-index, opacity < 1, transform (any value other than none), filter, isolation: isolate, will-change, mix-blend-mode, clip-path, mask, and several others. The most common culprits are opacity and transform.

Common z-index conventions: base content (1), sticky headers (100), dropdowns (200), tooltips (300), modals/overlays (1000), notifications/toasts (9000). Using a defined scale (like multiples of 100) makes it easier to insert new layers without conflicts.

No. Z-index only works on positioned elements — those with position: relative, absolute, fixed, or sticky. Setting z-index on a static element has no effect. This is one of the most common z-index mistakes.