CSS Formatter
Format CSS with readable indentation while keeping selectors, declarations, comments, values, and at-rule structure visible for review.
Make CSS easier to review
Compressed CSS can hide selectors, declarations, nested at-rules, comments, and long values on one line. This formatter presents a readable layout so you can inspect styles before using them in a page, component, or build.
Formatting changes presentation rather than proving that CSS is valid, efficient, accessible, or compatible with every browser. Keep the original stylesheet and compare a controlled diff.
Use a representative sample with selectors, multiple declarations, comments, custom properties, media queries, and quoted values when those constructs matter. Run the CSS parser, linter, and browser checks required by your workflow.
Formatting is not CSS validation
CSS consists of selectors, declarations, values, comments, at-rules, functions, custom properties, and blocks. Indentation can make their boundaries and nesting easier to follow.
A formatter arranges whitespace and tokens according to its parsing path. It does not prove standards conformance, specificity intent, accessibility, performance, security, or build-tool compatibility.
CSS values may contain strings, URLs, escapes, mathematical expressions, gradients, variables, and vendor extensions. Preserve exact values and test with the target browser and toolchain.
How to format CSS
- Paste a complete stylesheet or supported fragment into the source field.
- Run the formatter and inspect selectors, braces, declarations, comments, custom properties, functions, and at-rules.
- Compare selectors, property names, values, quotes, URLs, variable references, and rule order with the original.
- After formatting, run the CSS linter, build, accessibility checks, and browser tests required by the project.
- Remove private URLs, tokens, and user data from samples unless policy permits them.
Formatting method
- Read CSS tokens
The tool reads selectors, declarations, values, comments, blocks, functions, and at-rules that can be laid out.
- Apply block layout
Line breaks and indentation make rules, declarations, nested blocks, and media conditions easier to scan. The whitespace is presentation output.
- Preserve style values
Property values, strings, URLs, custom-property text, comments, functions, and rule order must remain tied to the source. Review a diff when exact text matters.
Exact parser recovery, dialect and vendor-extension support, comment handling, whitespace policy, and error wording should be confirmed with a live engine.
Read the formatted result
A successful result is a readable arrangement of the supplied CSS. Confirm selectors, declarations, values, comments, blocks, functions, and rule order against the source.
A failure means the documented formatting path could not handle the input. Do not infer exact parser support or recovery without runtime evidence.
If a browser, linter, or build later reports a problem, investigate syntax, cascade, compatibility, assets, and performance separately. Formatting is not optimization.
Common mistakes
Treating indentation as CSS validation can hide invalid values, specificity surprises, or accessibility problems.
Changing custom-property text, quoted strings, URLs, escapes, or rule order while formatting can change behavior.
Assuming one browser or vendor extension matches every toolchain can make the stylesheet misleading.
Pasting private URLs, tokens, or user-specific styles into a sample can expose sensitive data.
Limits and special cases
The documented capability is CSS presentation formatting. It does not guarantee standards validation, lint compliance, accessibility, security, performance, browser compatibility, or minification.
Custom properties, at-rules, vendor extensions, CSS functions, escapes, comments, large stylesheets, and whitespace-sensitive values should be tested with target tools.
Do not paste confidential production styles unless your handling policy permits it.
Examples
Format a simple rule
Can a compact CSS rule become readable?
Submit the compact rule.
The selector and declarations appear on separate indented lines.
Keep a class selector
How should a class rule be reviewed?
Format the class rule and inspect both declarations.
The class selector stays attached to its padding and border declarations.
Preserve a comment
What happens to a CSS comment?
Format the custom-property rule with its comment.
The comment remains above the root rule.
Format a media query
Can a nested media block be inspected?
Format the at-rule and its nested selector.
The condition, nested selector, and declaration have visible levels.
Keep a quoted value
Can a font family string stay intact?
Format the declaration and compare the quoted name.
The quoted font name remains part of the value.
Keep a URL value
Can a background URL remain unchanged?
Format the rule and inspect the URL function.
The URL remains inside the background-image value.
Frequently asked questions
Does formatting validate CSS?
No. Use the CSS parser, linter, build, accessibility checks, and browser tests required by the project.
Will formatting change the cascade?
It should change layout whitespace for supported input, but compare rule order and test the stylesheet because parsing and whitespace can matter.
Are property values preserved?
The examples keep values, strings, URLs, functions, and custom-property text. Review a diff when exact content matters.
Are comments preserved?
The examples retain comments in the formatted view. Confirm behavior for your exact input before relying on comments in a build.
Can it format a media query?
The example shows a nested at-rule. Confirm support for the dialect and syntax used by your stylesheet.
Does formatting improve CSS performance?
No. Use build analysis, coverage, browser profiling, and targeted optimization for performance work.
Can formatting repair invalid CSS?
Do not assume automatic repair. Correct the source deliberately and validate it with the target parser and browser.
What should I do after formatting?
Review a diff, run lint and build checks, test accessibility and browsers, and keep private data out of shared copies.