CSSTidy — CSS Formatter & Minifier Guides & Examples
Practical, no-fluff documentation for CSSTidy — CSS Formatter & Minifier — written by people who hit the problems first.
About CSSTidy
What csstidy.net actually does to your stylesheet, which characters its rewriter cannot see past, and where a real parser beats it.
CSSTidy Changelog
Dated changes to csstidy.net — formatter behaviour, accessibility fixes, and the string-handling limits found by running the tool against itself.
Contact CSTidy
Contact the operator of csstidy.net — minifier bugs, formatting output that changed meaning, and feature requests. One human mailbox, replies within two business days.
Beautify Is Not Format: Three Implementations, Same 23 Inputs
The shipped beautifier against js-beautify 2.0.3 and Prettier 3.9.10 on identical input, plus a 95 KB real file where the honest conclusion is that all three are idempotent and only one of them mangles strings.
CSS Formatters and Minifiers Compared: Which Ones Can Eat Your String
Lightning CSS vs cssnano vs clean-css vs Prettier vs this site — real parser or textual rewriter, maintenance dates from the registry, and the one input that separates them.
CSS Minification Best Practices: What Survives the Build Step
Quoted strings and comments, the safe order of transforms, why your minifier is eating characters, and what to assert in CI so it fails loudly.
CSS Cheat Sheet: Selectors, Specificity, and the Properties Worth Memorising
One printable screen - specificity maths, selector list, box model and layout one-liners, common @-rules, and what a formatter is allowed to touch.
Media Queries and Container Queries: When to Switch, and How to Migrate
Viewport vs container context, size containers, style queries, cqi units, and the migration path for a breakpoint-driven layout that has grown too many breakpoints.
CSS Custom Properties and Design Tokens: Fallbacks, @property, and What Does Not Cascade
How var() fallback chains actually resolve, why a custom property will not animate, @property registration, and the token layout that survives a theme switch.
Debugging CSS in DevTools: Specificity Conflicts, Struck-Through Rules, and Inherited Mystery
How to read the Computed panel properly, find the rule that is actually winning, diagnose inherited values you never set, and stop guessing at !important.
CSS Hacks That Still Work in 2026
Eleven short techniques - auto dark mode without a class, scroll shadows, has() validation, container queries, focus-restored links, and spacing that survives.
CSS Libraries in 2026: Bootstrap Grew 42%, Tailwind Grew 12.9×
npm download counts for the CSS frameworks and tooling people actually install, what the spread between component libraries and utility frameworks says, and what downloads cannot show.
Is CSS Minification Safe? Four Places Whitespace Is Content
Measured failure cases for regex-based CSS minifiers - data URIs, content strings, comments that matter, and why a round-trip test can agree on corrupted output.
The CSS Toolchain Is Maintained by One Person Each
Release dates, maintainer counts, and dependency weight for ten CSS packages from the registry. PostCSS handles 1.342B downloads a month with one publish account and shipped yesterday.
CSS Patterns and Gotchas: Collapse, Containment, and Cascade Traps
Why margins collapse but gaps do not, what overflow:hidden quietly breaks, stacking-context surprises, and the cascade rules that override specificity.
CSS Performance: Layout Thrash, Paint Costs, and the Properties That Are Cheap Now
Which CSS costs are real on a low-end device - containment, content-visibility, the transform/compositing tradeoff, and how to measure a stylesheet you cannot see.
CSS Resets in 2026: modern-normalize, @layer, and What Actually Needs Resetting
What a reset still has to do after UA styles improved, why @layer changes the answer, and the 20-line reset that survives contact with a design system.
CSS Selectors in Practice: :where, :is, :has, and the Ones Worth Using Daily
A working tour of modern selector syntax - specificity-zero wrappers, relational selection, functional pseudo-classes - with the compatibility notes for each.
CSS Tooling in 2026: A Parser Grew 130× and a Linter Grew 2.4×
npm download counts for CSS tools over 2024–2026, what the spread between parsers and linters implies about where CSS gets written, and what the numbers cannot show you.
Grid vs Flexbox: The Decision, Not the Feature List
One axis or two, which properties each layout owns, the subgrid and auto-fit patterns, and the cases where flex silently wins or loses.
CSS Minification Gotchas: 22 Inputs, Four Minifiers, Real Output
Every behaviour claim on this page came from running the shipped minifier and cssnano, Lightning CSS, CSSO, and Prettier over the same inputs under Node. Including the cases where this site's own tool loses data.
The /*! */ License Comment Your Minifier Deletes
/*! is the convention for 'keep this comment'. Measured against the shipped minifier and beautifier: one keeps it, one deletes it, and the difference is licensing, not bytes.
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