Minify only removes whitespace and comments, and Beautify/1 Line only change spacing and line breaks — neither changes what your CSS does. Optimise's safe clean-ups (zero-unit stripping, hex shortening, and the like) are value-level substitutions that keep the same meaning. The one exception is the optional shorthand conversion toggle under Optimise, which combines separate longhand properties (like the four margin sides) into a single shorthand — this is structural, so review the change list before relying on it.

Beautify gives you full indentation and one declaration per line — best for reading and editing. 1 Line / Rule keeps each selector's declarations together on a single line, a compact but still-readable middle ground. Minify removes all unnecessary whitespace and comments for the smallest file size, meant for production.

With Optimise on, a set of safe rules run automatically: named colors become hex codes, hex colors are shortened and lowercased, unnecessary zero units and leading/trailing zeros are trimmed, none borders become 0, and keyword font-weights become numbers. Turning on the extra "Shorthand conversion" option also merges individual side properties into their shorthand form when all four are present. Click any item in the Optimisations panel to see exactly what changed.

Yes — in Beautify mode, the Sort pill lets you order declarations alphabetically or in an idiomatic grouping (positioning, then box model, then border, background, typography, effects, and so on). Nested rules and blocks are always kept after plain declarations.

No. Formatting, optimising, file loading, copying and downloading all happen entirely in your browser — nothing is uploaded to a server.