Z-Index Stacking Visualizer
Visualize CSS z-index stacking contexts with an interactive layer builder. Add, reorder, and configure layers with names, z-index values, and stacking context settings. See the rendering order in a live visual preview, detect common issues like duplicate z-indices, and copy the generated CSS. Fully private, 100% free, and no signup required.
Layers (5)
Stacking Order
Why Use Our Z-Index Stacking Visualizer?
Visual Stacking Context Preview
See exactly how your layers stack with a live visual preview. Each layer is displayed with its actual z-index, showing which elements appear on top. The preview automatically updates as you add, remove, or reorder layers.
Smart Warnings & Best Practices
The z-index visualizer automatically detects common issues: duplicate z-index values, extremely high values (9999+), and missing stacking contexts. Each warning includes a clear explanation of the problem and how to fix it.
100% Private - No Upload
All stacking context visualisation happens locally in your browser. Your layer configurations never leave your device and are never sent to any server.
Free & No Limits
Create unlimited z-index stacking configurations with no signup, no subscription, and no usage caps. The z-index stacking visualizer is completely free forever with no ads blocking the interface.
Common Use Cases for Z-Index Stacking Visualizer
Debugging Stacking Issues
Frontend developers use the z-index stacking visualizer to debug elements that appear in the wrong order. Add your layers with their z-index values and instantly see the rendering stack - identify conflicts and fix them without trial and error in DevTools.
Modal & Overlay Planning
UI designers use the z-index stacking visualizer to plan modal dialog z-index architectures. Plan the overlay, modal content, and backdrop layers together, ensuring modals appear above navigation while remaining below critical alerts.
Design System Architecture
Design system teams use the z-index visualizer to define and document z-index scales for their component library. Establish clear z-index tiers for navigation, overlays, tooltips, modals, and notifications - ensuring consistency across all components.
Sticky & Fixed Position Layout
Layout designers use the z-index stacking visualizer to plan sticky headers, fixed sidebars, and floating action buttons. These positioned elements create new stacking contexts that need careful z-index management to layer correctly.
Dropdown Menu & Tooltip Systems
Designers use the z-index visualizer to plan nested dropdown menus and tooltip systems that must appear above all page content without breaking stacking contexts. Understand how each dropdown level creates a new stacking context.
Code Review & Documentation
Team leads and senior developers use the z-index stacking visualizer during code reviews to explain stacking context issues and document recommended z-index architectures. Share visual stacking diagrams in PR descriptions and documentation.
Understanding CSS Z-Index & Stacking Contexts
What is Z-Index?
Z-index is a CSS property that controls the stacking order of positioned elements along the z-axis (the axis coming toward you out of the screen). Elements with a higher z-index appear in front of elements with a lower z-index. Z-index only works on positioned elements - those with position: relative, absolute, fixed, or sticky. Our z-index stacking visualizer helps you understand and manage these relationships visually.
How Our Z-Index Stacking Visualizer Works
- Add and configure layers: Each layer represents a positioned element with a name, z-index value, colour, and stacking context setting. Add new layers, rearrange their order, or load one of the presets to get started.
- See the visual stack: The preview area shows all layers as overlapping boxes with their z-index values. Layers with higher z-index values appear on top. Enable the stacking context toggle to mark layers that create new stacking contexts.
- Review warnings and export CSS: The tool automatically detects potential issues like duplicate z-indices or missing stacking contexts. Copy the generated CSS for your layers with one click.
What Creates a New Stacking Context?
- Root element - the HTML element itself creates the root stacking context.
- Positioned elements with z-index - any element with position: relative, absolute, fixed, or sticky AND a z-index value other than auto.
- Opacity less than 1- elements with opacity < 1 create a new stacking context (used to isolate rendering).
- CSS transforms - any element with a transform other than none creates a new stacking context.
- CSS filters - elements with filter or backdrop-filter create new stacking contexts.
- will-change - the will-change property can create stacking contexts.
- contain - contain: layout or contain: paint create stacking contexts.
Why Stacking Contexts Matter
Stacking contexts are one of the most commonly misunderstood CSS concepts. When an element creates a new stacking context, its children's z-index values are scoped to that context - they can only overlap other elements within the same context. This is why a child with z-index 9999 can still appear behind a parent's sibling if the parent has a lower z-index in the root context. The z-index stacking visualizer makes this relationship clear by showing which layers create new contexts and how z-index values relate across the full stacking hierarchy.
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Frequently Asked Questions About Z-Index Stacking Visualizer
A stacking context is a group of elements that share a common parent and are stacked together. Elements within a stacking context are stacked relative to each other, and the entire context is stacked relative to sibling contexts. This means a child element with z-index 9999 inside a parent with z-index 1 will still appear behind a sibling of that parent with z-index 2. Stacking contexts are created by positioned elements with z-index, opacity less than 1, transforms, filters, and several other CSS properties.
If z-index: 9999 doesn't put your element on top, it's likely trapped inside a stacking context. Check if any ancestor element creates a stacking context (has position + z-index, opacity < 1, transform, filter, or will-change). Your element's z-index only applies within that ancestor's stacking context. To fix this, either move the element outside that ancestor in the DOM, or increase the ancestor's z-index.
Z-index is the property that sets where an element appears along the z-axis (front to back). A stacking context is the scope within which z-index values are compared. Think of stacking contexts as floors in a building: each floor (stacking context) has its own ordering, and the floors themselves are stacked. Without understanding stacking contexts, z-index values can seem unpredictable - which is exactly what the z-index stacking visualizer helps you understand.
Yes. In CSS, the z-index property only works on positioned elements (position: relative, absolute, fixed, or sticky). If you set z-index on a static (default) element, it will be ignored. The only exception is for CSS Grid and Flexbox items, where z-index can work without explicit positioning. The z-index stacking visualizer assumes all layers are positioned.
A recommended z-index scale keeps values spaced out to allow for future additions. A common approach: 0-9 for page content layers, 10-19 for headers and navigation, 20-29 for sticky elements, 100-199 for dropdown menus and tooltips, 200-299 for overlays and backdrops, 300-399 for modals, and 400+ for critical notifications and toasts. Using increments of 10 or 100 between tiers leaves room for intermediate values.
Yes. The z-index stacking visualizer is 100% free with no signup required, no premium features, and no usage limits. Create unlimited stacking configurations without any restrictions or hidden costs.
Yes. The z-index stacking visualizer is an excellent teaching tool. The visual preview with overlapping layers makes it easy to demonstrate how z-index and stacking contexts work. The automatic warnings help students understand common mistakes, and the stacking order table provides a clear, numbered listing of the render order from bottom to top.
The root stacking context is the default context created by the HTML element itself. All elements that do not create their own stacking context exist within the root context or a descendant context. The root context is always at the base of the stacking hierarchy. The z-index stacking visualizer includes the root context as the first layer by default, representing the page background.