mgbrowser v0.9.27 Experimental Preview

mgbrowser v0.9.27 Experimental Preview

CSS layout fidelity, anti-aliased border-radius rendering and rounded clipping,
full CSS 2.1 Appendix E stacking contexts and z-index paint order, position: absolute hypothetical static positioning across block/inline/flex/grid and
position: sticky clamping, direction: rtl, CSS Sizing 4 aspect-ratio,
linear calc(% + px) in flex/grid, CSS 2.1 float/clear and BFC float
avoidance, overflow: auto | scroll and table-cell clipping, general
::before/::after pseudo-elements, visibility: collapse, and CSSOM
container-query length units. Honest upstream WPT coverage advances from 339
to 528 PASS / 421 FAIL / 62 UNSUPPORTED of 1,011 (+189 net new passes,
zero losses) on the static reftest lane and from 15/16 (77/79) to 16/16
files and 79/79 final subtests (100%) on the Window parsing lane.
Exact-source publication and public-install receipts are recorded in the dated
work log.

Linux x86_64 / X11 or XWayland, glibc 2.35 or newer. Rust 1.91.1, locked
dependencies, Apache-2.0 license, and pure-Rust implementation backends (zero
new crate dependencies).

CSS Layout Fidelity & WPT Coverage (v0.9.27)

• Rounded Corners & Clipping (crates/mg-sparkle/src/paint.rs, styled_layout.rs):
  • Implements CSS Backgrounds 3 §4.5 elliptical corner resolution, overlap
    scale factor f, inner padding/content radii, 4×4 supersampled boundary
    anti-aliasing without outer background bleed, diagonal per-side corner
    borders, and stackable rounded CanvasClip masking across fills, text,
    gradients, images, and overflow != visible, while preserving an exact
    zero-overhead fast path when all outer radii are zero.
• Stacking Contexts & CSS 2.1 Appendix E Painting Order (crates/mg-sparkle/src/styled_layout/stacking.rs):
  • Establishes stacking contexts for opacity < 1.0, position: fixed | sticky,
    and numeric z-index on positioned boxes and flex/grid items, ordering own
    backgrounds/borders, negative z-index child contexts, in-flow blocks,
    floats, inline/atomic-inline and order-sorted flex/grid items, DOM-ordered
    z-index: auto positioned pseudo-contexts interleaved with z-index: 0
    contexts, and positive z-index child contexts with clip-safe paint and hit
    reordering.
• Positioned & Sticky Layout (crates/mg-sparkle/src/styled_layout/positioned.rs, formatting.rs):
  • Computes hypothetical static positions for position: absolute | fixed with
    auto insets across block, inline, flex, and grid formatting contexts (LTR
    and RTL), plus position: sticky clamping within scrollports and containing
    block content boxes.
• RTL, aspect-ratio, Flex/Grid calc(), Floats, Overflow, Pseudo-Elements & Collapse:
  • direction: rtl across block horizontal margins, bidi inline runs, table
    columns, and Taffy flex/grid axes; CSS Sizing 4 aspect-ratio transfer and
    automatic minimum sizing; linear calc(% + px) in flex/grid; CSS 2.1 §9.5
    float / clear and BFC float avoidance; overflow: auto | scroll and
    table-cell padding-box clipping; general ::before and ::after
    pseudo-element cascade and layout materialization; and visibility: collapse
    flex struts and table tracks.
• CSSOM Container-Query Units & Upstream WPT Scores (crates/mg-sparkle/src/style/declarations.rs):
  • Supports cqw, cqh, cqi, cqb, cqmin, and cqmax in CSSOM
    CSSStyleDeclaration parsing and serialization without C++ bindings,
    bringing the pinned WPT Window parsing lane to 16/16 passing files and
    79/79 passing final subtests, while lifting the pinned WPT static flexbox
    reftest lane to 528 PASS / 421 FAIL / 62 UNSUPPORTED of 1,011 (+189
    new passes, 0 regressions).