Units

A length is an EVGUnit: a number, a unit type, and the pixels it resolved to.

Suffix	Resolves against
px (or a bare number)	Itself. The CSS reference pixel
%	The parent’s width on a width property, the parent’s height on a height property
hp	The parent’s height, on any property
em	The element’s own font size
rem	The root font size
vw vh	The layout’s page size (EVGLayout.setPageSize)
fill	Whatever space is left
pt pc in mm cm	96/72, 16, 96, 96/25.4, 96/2.54 px — as CSS defines them

vw and vh are the viewport, which is a different thing from the parent. On paper that viewport is the page area (the sheet less its margins), because that is what CSS says viewport-percentage lengths mean in paged media. So 100vh is the text column on A4 and the window in a browser.

Resolution order

Units are resolved during layout, not during parse:

1. Pixels — used directly.
2. Percentage — against the parent’s inner size for that axis.
3. em — fontSize × value.
4. hp — against the parent’s inner height.
5. fill — expands into leftover space.

resolveUnits refuses to run twice on the same element, so a percentage is never resolved against an already-resolved parent. A second layout pass must start from resetLayoutState(). layout() calls that.

Unrecognised suffixes

An unrecognised suffix leaves the unit unset (auto). It does not fall through to pixels. 10ch is not 10px. ch and ex are not implemented. calc() is not implemented. Each of those is a warning through EVGReject, not a silent width: 100%.