CSS Container Query Builder

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.

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.

.card { grid-template-columns: 1fr 1fr; }

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.