v2.3.1

Calls that compiled into CSS a browser drops, or into a media or container
condition that can never match, now stop the build with a message naming what
the argument takes. Every new refusal was checked in Chrome 152 against the CSS
the same call produced on 2.3.0, and an error was added only where that CSS was
dropped or did nothing. var(), calc() and the other CSS functions are still
accepted. Two calls that produced broken CSS now produce working CSS instead.

• Fixed: breakpoint, remove, container-query and screen-agent
  refuse a size no condition can match, such as a word that is not a breakpoint
  key, a percentage or an angle. validateBreakpoint refuses a word that is
  not a key in $map-for-breakpoints, and still returns lengths, percentages,
  functions, sizing keywords and null as they are.
• Fixed: only and except refuse a position with a unit, a fraction or
  0, which the browser drops or which matches nothing. 3n is accepted.
• Fixed: position, ellipsis, resizable, radial-gradient and
  font-face refuse keywords the browser drops, and write a valid quoted
  keyword, such as "sticky", without its quotes.
• Fixed: background-image, brand-logo and text-image refuse a list or
  a non-string image. background-dots and background-stripes quote an image
  path holding a space, a parenthesis or a quote, which the browser dropped
  unquoted. sprite checks its path in the two-argument form too.
• Fixed: background-stripes no longer turns 0.25turn into
  0.25turndeg. An angle in grad, rad or turn is written as it is, and a
  unit that is not an angle raises.
• Fixed: the colour arguments of focus-ring, text-stroke, triangle,
  linear-gradient, text-gradient, radial-gradient, background-image,
  background-dots and background-stripes refuse a value that is not a
  colour. System colours such as Canvas and contrast-color(), which
  triangle used to refuse, are accepted.
• Fixed: lengths are checked against what each property keeps in sizer,
  circle, brand-logo, ellipsis, focus-ring, text-stroke, triangle,
  border-radius, background-dots, background-stripes, scissors (through
  validateScissors), sprite, columnizer and adaptive: for example a
  negative width, 5% as an outline width, auto as a max-width, or 10deg
  wherever a length goes.
• Fixed: adaptive(0) wrote calc(576px - 0 * 2) and columnizer(3, 0)
  wrote (3 - 1) * 0, a number where calc() needs a length, and the browser
  dropped both. They now write 0px.
• Updated: position raises on an offset the browser drops instead of
  warning through validateLength. That warning also fired for working values
  such as AUTO and revert-layer, and said nothing about 10deg or url().
  validateLength itself still warns.

Full changelog: v2.3.0...v2.3.1