The `font` shorthand supports the full `font-weight` algorithm

[yisibl]

WPTs

• Shorthand: https://wpt.live/css/css-fonts/variations/font-shorthand.html

• font-weight valid: https://wpt.fyi/results/css/css-fonts/parsing/font-weight-valid.html?label=master&label=experimental&aligned

• https://wpt.live/css/css-fonts/parsing/font-weight-computed.html
  Note: calc <= 0 always evaluates to 1.

  test_computed_value('font-weight', 'calc(0)', '1');
  test_computed_value('font-weight', 'calc(-100)', '1');
  

Note: CSS font-weight: lighter/bolder is somewhat unique, as its computed value inherits from the parent element. However, its behavior in Canvas requires further testing.

See WPT test: https://wpt.live/css/css-fonts/parsing/font-weight-computed.html