Skip to main content
Stylesheets

CSS Formatter

Reindent simple CSS with two spaces by inserting line breaks around braces and semicolons, while showing browser stylesheet diagnostics before copy or download. Helpful for developers cleaning minified styles, reviewing auto-generated CSS, or preparing code for pull requests. Catches basic syntax issues inline.

Web formatters

In brief

Beautify straightforward CSS locally, but recognize that the formatter is a text heuristic—not a CSS Syntax parser—and can alter semicolons or braces inside strings, URLs, comments, and complex constructs.

What this tool supports

  • The workspace accepts pasted or imported .css text and is reliable only for straightforward rules whose braces and semicolons are structural.
  • It adds a space before {, a line after { and ;, a line around }, trims lines, removes blank lines, and indents nested brace depth by two spaces.
  • The output remains CSS text and can be copied or downloaded as formatted.css; the browser linter is advisory and does not prove full semantic equivalence.
  • After review, combine the stylesheet with markup in HTML Formatter and inspect the sandboxed preview.
  • It is not a standards-complete tokenizer, parser, minifier, prefixer, optimizer, or semantic validator.

How to use CSS Formatter

Complete a verifiable CSS Formatter workflow in this browser.

  1. 1

    Step 1

    Provide the exact input

    The workspace accepts pasted or imported .css text and is reliable only for straightforward rules whose braces and semicolons are structural.

  2. 2

    Step 2

    Set the available controls

    No indent-width or minify control is exposed; output uses two spaces.

  3. 3

    Step 3

    Run the operation

    It adds a space before {, a line after { and ;, a line around }, trims lines, removes blank lines, and indents nested brace depth by two spaces.

  4. 4

    Step 4

    Verify the result

    Diff source and output, then parse and render the result in target browsers—especially when strings, data URLs, custom properties, comments, nesting, or at-rules are present.

  5. 5

    Step 5

    Continue or export

    After review, combine the stylesheet with markup in HTML Formatter and inspect the sandboxed preview.

Common mistakes

Formatting SCSS, Less, or template syntax as if it were plain CSS

Consequence: Interpolation braces, nested language constructs, or template delimiters can be split and indented as structural CSS because this formatter performs text substitutions rather than parsing the source language.

Fix: Compile the source to CSS first, or use a formatter that parses the actual preprocessor or template grammar.

Replacing a production stylesheet because the preview has no diagnostic

Consequence: Browsers recover from many CSS errors, and the advisory CSSOM check can accept a stylesheet whose strings, custom properties, comments, or nested constructs were changed by the whitespace heuristic.

Fix: Diff source and output, parse the result with production tooling, and render representative pages in every supported browser before replacing the original.

Overlooking this edge case: What happens to semicolons inside a quoted data URL?

Consequence: The heuristic replacement can insert a newline there because it does not tokenize strings before replacing semicolons.

Fix: Do not use this formatter on such content without a diff and browser parse check; use a real CSS parser for complex code.

Best practices

  • Diff every nontrivial result, with special attention to quoted strings, data URLs, custom-property values, comments, at-rules, and nesting.
  • Render a representative page in each target browser because CSS error recovery can hide damage that the advisory diagnostic does not report.
  • Keep the original stylesheet under source control so formatting can be reviewed and rolled back without reconstructing lost whitespace.
  • Use a parser-based formatter tied to the project’s CSS or preprocessor grammar for automated production rewrites.

Connected workflows

Format and browser-check a stylesheet

CSS FormatterHTML Formatter with PreviewHEX, RGB and HSL Color Converter

After review, combine the stylesheet with markup in HTML Formatter and inspect the sandboxed preview.

  1. Format only plain CSS whose braces and semicolons are structural
  2. Diff strings, URLs, comments, custom properties, nesting, and at-rules against the source
  3. Combine the reviewed stylesheet with representative markup in HTML Formatter
  4. Parse and render the result in every target browser

Browser limitations

  • Text substitutions are not syntax-aware.
  • Entire source and output are kept in memory.
  • Browser CSSOM diagnostics can recover from invalid CSS and miss authoring errors.

Authoritative resources

CSS Syntax Module Level 3Publisher: W3C · Reviewed: 2026-07-26CSSOMPublisher: W3C · Reviewed: 2026-07-26

Concrete examples

Input
.a{color:red;margin:0;}
Result
.a { color:red; margin:0; }

The heuristic places each declaration on its own two-space-indented line; it does not normalize spacing after the colon.

Frequently asked questions

Can I use this formatter for SCSS, Less, or template-generated styles?

The workspace accepts pasted or imported .css text and is reliable only for straightforward rules whose braces and semicolons are structural.

What happens to semicolons inside a quoted data URL?

The heuristic replacement can insert a newline there because it does not tokenize strings before replacing semicolons.

Does a clean-looking result prove valid CSS?

It is not a standards-complete tokenizer, parser, minifier, prefixer, optimizer, or semantic validator.

Which CSS constructs need a source-to-output diff?

Diff source and output, then parse and render the result in target browsers—especially when strings, data URLs, custom properties, comments, nesting, or at-rules are present.

Is pasted CSS or an imported .css file uploaded?

CSS text and browser diagnostics stay in this tab and are not uploaded. Offline use works after assets are cached; file selection, clipboard, and download are explicit.

How can I review the formatted stylesheet together with its HTML?

After review, combine the stylesheet with markup in HTML Formatter and inspect the sandboxed preview.

Privacy and offline behavior

CSS text and browser diagnostics stay in this tab and are not uploaded. Offline use works after assets are cached; file selection, clipboard, and download are explicit.