v0.1.14514 Aug 2026·Rendering, JavaScript & JIT

Grid tracks join the exact-tiling guarantee

The exact-tiling invariant introduced in 0.1.144 for flex rows and float columns now covers CSS grid as well. A grid template of equal fr tracks is the canonical seam case in other engines - the reference browser's own DevTools shows three 1fr thirds of a 100px grid ending at 100.008 pixels, a fraction past the container - and percentage templates carry the same rounding. Floati now closes any full track set bit-exactly on the container edge: fr tracks, percentage tracks, and stretched auto tracks, in explicit templates and implicit columns both. The same gate discipline applies: sweeps of two to twelve tracks across eight hostile window widths asserting bit equality, and the one blessed render this changed was inspected pixel by pixel before re-blessing. The overall score holds at 57 - an invariant, not a coverage move.

Parity with the reference browser

74overall, as of v0.1.343

Web APIs / DOM surface42

Security architecture66

GPU / graphics acceleration68

DevTools / extensions72

Networking85

Media85

Accessibility85

Real-world site compatibility99

HTML parsing100

CSS parsing + selectors100

Layout: block / flex / grid / tables / writing-modes100

Paint + visual100

JavaScript language100

JavaScript performance (JIT)100

HTML parsing100

What changed 3 changes

Rendering	A shared closing snap for grid track sets (grid::snap_closing_track): when the tracks plus gaps fill the container to within rounding noise, the last track is nudged by units-in-the-last-place until the accumulated edge equals the container edge as the same 32-bit float. Under- or over-full track sets - a content-sized grid under justify-content: center, a min-content floor forcing overflow - are untouched.
Rendering	Applied to both column paths: explicit grid-template-columns and the implicit-columns path that grid-auto-flow builds, so utility grids and auto-flowing card grids close exactly too.
JavaScript & JIT	Two new gate sweeps (fr_grid_tracks_tile_exactly, percentage_grid_tracks_tile_exactly) assert shared edges and exact closure as bit equality for repeat(N, 1fr) and percentage templates, N from 2 to 12, at eight float-hostile widths. The one blessed trophy this moved was a single pixel column - an implicit grid column edge now closing exactly - verified with an old-versus-new pixel diff before blessing. Conformance stays 6375 of 6375.