[tannevaled]

Problem

white-space: pre-wrap and pre-line were parsed as pre (css/parse.go:789), so a block using them never wrapped. break-spaces was not parsed at all. Marp themes put code in pre with white-space: pre-wrap.

Spec read

• CSS Text 3 §3 table (new lines / spaces / wrapping / end-of-line spaces):
  • pre-wrap: preserve, preserve, wrap, hang.
  • break-spaces: preserve, preserve, wrap, wrap (spaces take room).
  • pre-line: preserve, collapse, wrap, remove.
• §4.1.2: preserved spaces at the end of a line hang under pre-wrap; under break-spaces they cannot hang or collapse.
• §5: under pre-wrap the wrap opportunity is at the end of a space run; under break-spaces it is after every space.

Change

• css.WSPreWrap, WSBreakSpaces, WSPreLine and WhiteSpace.PreservesSpaces().
• appendWords now uses the text's own inherited white-space:
  • pre-wrap: each newline is a forced break. Leading indentation stays in the first word. Each inner space run becomes the next word's SpaceBefore at its real width, so it is a wrap opportunity and hangs at a line edge. A line of only spaces hangs entirely.
  • break-spaces: spaces stay in the previous word's width (they take room), and the next word gets a new InlineItem.BreakBefore opportunity that glueRun honours. Breaking between two spaces of one run is not modelled.
  • pre-line: normal collapsing per line, with newlines as forced breaks.
• Side effect, spec-aligned: a white-space: normal span inside <pre> now collapses (its own value decides). The block's no-wrap placement for pre is unchanged.
• Min-content treats only pre and nowrap as unbreakable.

Tests

• TestWhiteSpaceWrappingValues (RenderHTML + script measuring boxes): pre-wrap, break-spaces and pre-line blocks wrap; pre-wrap keeps spaces and indentation; pre-line collapses spaces; newlines are kept for all three. Failed on main (no wrapping, pre-line kept spaces, break-spaces lost the newline). pre stays one line (control).
• Layout unit test of the produced items (hanging, BreakBefore, tabs, blank lines, normal-in-pre); css test of the keywords. css 99.5%, layout 100%.

🤖 Generated with Claude Code