What formatting settles
Most CSS argument is about layout of the text: whether a space follows the colon, whether a single declaration goes on one line, where the closing brace sits. A formatter answers all of it the same way every time, which removes the argument rather than winning it.
What it will not do
- Reorder properties. In CSS order is meaning.
marginfollowed bymargin-topis not the same as the reverse. - Merge or remove rules. Two rules with the same selector may be separated by a third that matters.
- Rename anything. Class names, custom properties and values come out exactly as they went in.
Those are optimiser jobs, and an optimiser needs to understand the cascade. A formatter that guessed at them would occasionally break a page.
Reading someone else's stylesheet
Minified CSS is still valid CSS. Pasting a vendor bundle here and formatting it is the quickest way to find out what a third-party widget is actually doing to your layout.
Questions
Does formatting change what the stylesheet does?+
No. Whitespace between declarations is insignificant in CSS, and nothing is reordered or renamed — selectors, properties and values come out identical. Only the layout of the text changes.
Will it sort my properties alphabetically?+
No, and deliberately. Property order matters in CSS: a shorthand followed by a longhand overrides it, and reordering silently changes the result. Sorting is a job for a linter with knowledge of that, not a formatter.
Does it handle SCSS and Less?+
Prettier's postcss parser accepts nested syntax, so both format correctly, including nesting and variables.
What about minified CSS I want to read?+
Paste it — a minified stylesheet is valid CSS and comes back readable. That is the fastest way to understand a vendor file you did not write.