FSE: inline block styles minification issues with calc()

[Sandstromer]

Description

In 10.1 the loading method of block styles on the frontend was changed, see #28358

There is an issue with the minified inline styles, specifically the removal of spacing in calc() functions.
e.g. the columns stylesheet contains flex-basis:calc(50% - 1em)
whereas the minified inline style now renders the same as flex-basis:calc(50%-1em) with the required spacing stripped out, resulting in an invalid value.

WordPress information

• WordPress version: 5.6.2
• Gutenberg version: 10.1.0
• Are all plugins except Gutenberg deactivated? Yes
• Are you using a default theme (e.g. Twenty Twenty-One)? Yes - TT1Blocks

[gziolo]

@aristath, any hints on how it could be resolved? Well, I know that one of the following regular expressions need some tweaks:

gutenberg/lib/blocks.php

Lines 293 to 294 in 771a45b

	$re1 = '(?sx)("(?:[^"\\\\]++|\\\\.)*+"|\'(?:[^\'\\\\]++|\\\\.)*+\')|/\\* (?> .*? \\*/ )';
	$re2 = '(?six)("(?:[^"\\\\]++|\\\\.)*+"|\'(?:[^\'\\\\]++|\\\\.)*+\')|\\s*+ ; \\s*+ ( } ) \\s*+|\\s*+ ( [*$~^|]?+= | [{};,>~+-] | !important\\b ) \\s*+|( [[(:] ) \\s++|\\s++ ( [])] )|\\s++ ( : ) \\s*+(?!(?>[^{}"\']++|"(?:[^"\\\\]++|\\\\.)*+"|\'(?:[^\'\\\\]++|\\\\.)*+\')*+{)|^ \\s++ | \\s++ \\z|(\\s)\\s+';

[aristath]

Pushed a fix in #29554, pending review.