CSSフォーマッター
トレンド 🔥CSSコードをフォーマット・圧縮
CSSフォーマッター の使い方
- 1入力エリアに CSS コードを貼り付ける
- 2フォーマットまたは最小化を選択
- 3処理済み CSS を確認
CSSフォーマッター について
CSS フォーマッターは CSS コードをフォーマットおよび最小化するツールです。プロパティを整理し、ルールをフォーマットします。CSS3 と現代的な構文をサポートします。
CSSフォーマッターの主な機能
- Beautify CSS with consistent indentation and property-per-line formatting
- Minify CSS by removing whitespace, comments, and redundant characters
- Handles media queries, pseudo-classes, and keyframe animations
- Preserves CSS custom properties (variables) and calc() expressions
- Works with plain CSS — complete stylesheets and individual rulesets
- Works entirely in-browser — no server uploads
- One-click copy for formatted or minified output
- Shows character count reduction achieved by minification
使用例
Beautify minified CSS from a production bundle
Format a compressed CSS file to understand its structure and find a specific rule.
入力
.btn{display:inline-block;padding:8px 16px;background:#007bff;color:#fff;border-radius:4px}出力
.btn {
display: inline-block;
padding: 8px 16px;
background: #007bff;
color: #fff;
border-radius: 4px;
}Minify a stylesheet for production deployment
Strip whitespace and comments from a development CSS file before deploying.
入力
Formatted CSS file with comments, ~80 lines
出力
Single-line minified CSS — ~40% size reduction before Gzip
主な使用ケース
- Formatting minified CSS files downloaded from a CDN for debugging
- Reading CSS copied from browser DevTools by reformatting it cleanly
- Minifying CSS stylesheets before deployment to reduce page load time
- Understanding third-party component CSS by beautifying their styles
- Preparing CSS snippets for documentation and technical blog posts
- Comparing formatted and minified CSS to identify whitespace-only differences
トラブルシューティング
Minified CSS still looks large
解決策
CSS minification removes whitespace but not unused rules. For more aggressive reduction, consider a CSS purging tool like PurgeCSS that removes rules not used in your HTML.
Formatted output breaks multi-line values like box-shadow
解決策
Some CSS properties accept multi-value syntax. A good formatter preserves these values intact. If output seems incorrect, compare with the original to see if value meaning changed.
SCSS or Less variables cause formatting errors
解決策
The tool handles standard CSS. SCSS variables ($var), Less variables (@var), and mixins may not format correctly. Compile your preprocessor styles to CSS first, then format.
よくある質問
Does it handle SCSS or Less?
The tool handles standard CSS. SCSS and Less syntax (variables, mixins, nesting) may not format correctly. Compile your preprocessor code to CSS first, then format the output.
Will minifying CSS break my styles?
No. Minification only removes whitespace and comments — it does not change any property names, values, or selectors. The resulting CSS is functionally identical to the original.
Does it support CSS custom properties (variables)?
Yes. CSS custom properties like --primary-color: #007bff and var(--primary-color) are treated as standard CSS and formatted or minified without modification.
Can I format a single CSS rule instead of a whole file?
Yes. Paste any CSS snippet — a single ruleset, a media query block, or an entire stylesheet — and the formatter will handle it correctly.
How much does CSS minification reduce file size?
Whitespace removal typically reduces CSS files by 20–40%. Combined with Gzip or Brotli compression at the server level, the total reduction is often 60–80% compared to the uncompressed formatted source.
Are CSS comments removed during minification?
Yes. Standard CSS comments (/* ... */) are removed during minification. If you have license comments that must be preserved, add them back manually or use a build tool that supports comment preservation.
Is my code sent to a server?
No. All formatting and minification is performed locally in your browser. Your CSS code never leaves your device.
Does it validate CSS syntax?
The formatter will produce incorrect output for syntactically invalid CSS but does not report specific errors. For CSS validation, use the W3C CSS Validation Service which provides detailed diagnostic messages.