CSS Formatter and Minifier は何をしますか？
CSS Formatter and Minifier はブラウザ上でデータを整形・検証するツールで、結果と制限を明確に示します。 検証済みの機能： Prettier CSS formatting, CSSO minification, Syntax error reporting, Local CSS download.
Formatting and minification serve different stages
Use formatting for code review, maintenance, and debugging. Use minification for a tested delivery artifact; keep the readable source under version control because optimized output is intentionally harder to edit.
使い方
- Choose Format CSS for a readable stylesheet or Minify CSS for a compact production-oriented result.
- Paste CSS no larger than 2 MB into Input and select Convert.
- Review the result and any syntax error, then copy it or download css-output.css.
実際の入出力例
Format and then minify a compact rule
入力
.card{display:grid;gap:16px;padding:0px 16px;color:#ff0000}出力
.card {
display: grid;
gap: 16px;
padding: 0px 16px;
color: #ff0000;
}
Minified: .card{display:grid;gap:16px;padding:0 16px;color:red}Prettier normalizes layout without trying to shorten values. CSSO parses the stylesheet, removes redundant units, and selects shorter equivalent color notation.
一般的なエラーと対処
| 症状 | 原因 | 対処 |
|---|---|---|
| Formatting reports a line and column error. | A declaration, brace, comment, at-rule, or selector is incomplete or invalid for CSS syntax. | Correct the first reported syntax error and run the formatter again; later errors may be consequences of the first one. |
| The minified file looks different in the browser. | The stylesheet depends on unusual cascade ordering, browser hacks, or restructuring-sensitive selector interactions. | Compare against the original in supported browsers and keep formatted CSS when an optimization is not safe for the project. |
Important behavior of CSS Formatter
このツール固有の制限： Minification can merge or restructure equivalent rules; always regression-test visual output and cascade behavior in the target site.
標準と実装の参考資料
- Prettier documentation (opens in a new tab)Documents the widely used formatter and its CSS parser used by Format CSS.
- CSSO official repository (opens in a new tab)Documents AST-based CSS cleaning, compression, and rule restructuring used by Minify CSS.
- W3C CSS Snapshot (opens in a new tab)Provides the standards overview for CSS specifications and syntax modules.
CSS Formatter — FAQ
Does the CSS Formatter upload my input?
No. Processing runs in the current browser tab, and the page does not send tool input to a KitLumi processing endpoint.
What input does the CSS Formatter accept?
It accepts one CSS stylesheet up to 2 MB. The workspace checks the input and reports malformed or unsupported values before it produces a result.
What does the CSS Formatter produce?
It produces Prettier-formatted CSS or CSSO-optimized minified CSS. Copy and download controls appear when the output format supports them.
What limitation should I know?
Minification can merge or restructure equivalent rules; always regression-test visual output and cascade behavior in the target site.
更新内容
実質的な更新： CSS Formatter: Added Prettier CSS formatting, CSSO minification, Syntax error reporting, Local CSS download, responsive controls, explicit runtime disclosure, and task-specific examples and limitations.