#454 · Developer Tool

CSS Box Shadow Generator

Assemble a CSS box-shadow with horizontal offset, vertical offset, blur, spread, color, opacity, and inset mode. The generated declaration uses rgba() so opacity stays separate from the selected color. Invalid hex colors and negative blur radii are rejected before output is produced.

Developer Input

Shadow layers
Ad space

How to use this developer tool

  1. Enter the source text or selector shown above.
  2. Adjust the controls for the CSS or JavaScript result you need.
  3. Select the generate or convert button, or press Ctrl/Cmd + Enter.
  4. Review the summary before copying or downloading the output.

What this developer tool does

The output is generated locally from the current input and settings. It is formatted as a complete snippet where the tool has enough context, so it can be copied into a stylesheet or JavaScript source file.

Assemble a CSS box-shadow with horizontal offset, vertical offset, blur, spread, color, opacity, and inset mode.

No source text is sent to a server. Browser support and surrounding stylesheet rules can still affect the final rendered result.

Example

Load the sample, keep the default controls, and run the tool. The output panel returns a CSS snippet that matches those values, along with tool-specific metrics.

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Use cases

  • Draft a declaration without remembering compact syntax.
  • Compare option changes before committing CSS.
  • Create a reproducible snippet for documentation or code review.
  • Catch invalid ranges and malformed settings early.

Tips for reliable output

  • Start with the sample to see the accepted input shape.
  • Use finite values and keep units consistent.
  • Test generated CSS with the writing mode and container size used by the project.
  • Check browser support when adopting newer CSS features.
  • Keep the downloaded snippet with the component it styles.

Processing details

Processing runs entirely in the browser. Numeric fields are converted with Number(), ranges are validated, and the output is assembled only after the tool-specific checks pass.

This page checks the values it generates, but it is not a complete CSS parser or browser rendering engine. Project cascade, inheritance, vendor support, and invalid declarations entered as free text may require separate testing.

Frequently asked questions

Why is a negative box-shadow blur rejected?

The generator validates the relevant input and emits copy-ready syntax. Its processing note explains any important boundary or assumption.

What is the difference between spread and blur?

The generator validates the relevant input and emits copy-ready syntax. Its processing note explains any important boundary or assumption.

How is the selected hex color converted to rgba()?

The generator validates the relevant input and emits copy-ready syntax. Its processing note explains any important boundary or assumption.

Can the generated shadow be inset?

The generator validates the relevant input and emits copy-ready syntax. Its processing note explains any important boundary or assumption.

Can I create multiple shadow layers at once?

The output targets the syntax shown by the controls. Review it in the browser versions and project context you support.

Output reference

ItemValue
FormatCSS
ExecutionLocal browser
ShortcutCtrl/Cmd + Enter

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