Add font-variant property (normal/small-caps) with correct per-character-case
rendering: lowercase chars rendered uppercased at 0.8x size, uppercase/non-letter
chars at full size. Fix font shorthand to validate mandatory font-family and reject
invalid line-height after /. Wire up actual x-height from font metrics in layout
measurement. Add font-variant to ::first-line pseudo-element support. Deduplicate
rasterizer text rendering. Add ex unit to grid template parsing tables.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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