Visually manage z-index layers, debug stacking conflicts, generate normalized z-index scales
Zero Dependencies · Works Offline📝 Z-Index Layer Definitions
What Can the CSS Z-Index Manager Do?
The CSS Z-Index Manager is a free online frontend development tool that helps developers visually manage z-index layers in their projects, debug stacking conflicts, and generate normalized z-index scales and CSS variables. Supports custom layer definitions, auto-normalization, visual preview, and CSS code generation. All processing runs locally in your browser—no data is ever uploaded.
Core Features
- Layer Definition: Custom names and z-index values for quick project layer setup
- Visual Preview: Intuitive display of stacking relationships
- Auto-Normalize: Reassign z-index values by 10/100/1000 base
- CSS Generation: Output CSS variables and class names for direct use
- Conflict Detection: Flag duplicate or conflicting z-index values
How to Use
1. Define layers in the input box, one per line: name:z-index-value.
2. Click "Generate" to see the visual preview.
3. Click "Normalize" to reassign z-index values by base.
4. Copy the generated CSS variable code to your project.
Use Cases
Project Z-Index Standards
Frontend teams establish unified z-index layer standards, avoiding random use of extreme values like 9999.
Stacking Conflict Debug
When modals are obscured by other elements, use this tool to map layer relationships and locate conflicts.
CSS Variable Generation
Generate z-index CSS variables for unified project references, making maintenance and adjustments easier.
Technical Background
CSS z-index controls the stacking order of positioned elements on the Z-axis, only working with position: relative/absolute/fixed/sticky. Stacking Context is a 3D CSS rendering concept—properties like opacity<1, transform, filter, and will-change create new stacking contexts. Child z-index only compares within the same stacking context. Best practice: use CSS variables for z-index management (e.g., --z-modal: 40) for global adjustability. Avoid extreme values like 9999; use a normalized layer system instead.
❓ FAQ
What is z-index?
z-index controls positioned element stacking order on the Z-axis. Higher values render in front. Only works with non-static position.
Why isn't z-index working?
Common: no position property, parent creates new stacking context, or elements are in different contexts.
What is a stacking context?
A 3D CSS concept determining rendering order. opacity<1, transform, filter create new contexts.
How to normalize z-index?
Use multiples of 10/100/1000 as intervals: 10=base, 20=content, 30=header, 40=overlay, 50=modal.
Is data uploaded?
No. All processing runs locally in your browser.