Skip to main content

Known Issues

Layout​

z-index Stacking Contexts​

Symptom: A deeply nested z-index: 999 element paints behind a shallow z-index: 1 element in a different subtree.

Cause: Sibling sort by z-index works correctly, but there are no independent stacking contexts. Cross-branch ordering follows tree DFS, which can override z-index expectations.

Workaround: Keep z-indexed elements as siblings within the same parent.

Border Style Rendering​

Symptom: border-style: double, groove, ridge, inset, outset render as solid lines.

Cause: Only solid, dashed, dotted, none, and hidden are implemented in the quad pipeline shader.

Dashed/Dotted on Elliptical Corners​

Symptom: Dashed/dotted borders on elements with non-uniform border-radius (elliptical corners) show straight segments at corners.

Cause: The patterned border shader only follows curved corners for uniform-circular radii.

em/rem Default Size​

Symptom: em and rem units use exactly 16px when no explicit font-size is inherited.

Cause: UA stylesheet font-sizes are not globally applied; the root font-size is not resolved until layout. A hard-coded 16px fallback is used.

Position: Sticky​

Symptom: position: sticky behaves the same as position: relative.

Cause: Sticky positioning logic is not implemented. The element is offset like relative but doesn't react to scroll position.

Parser​

Unknown Tags​

Symptom: Unknown HTML tags cause their entire subtree to be silently dropped.

Cause: The parser only recognizes ~96 tag names. Unrecognized tags (e.g., <figure>, <menu>, <q>) are dropped at tree-build time.

Whitespace Handling​

Symptom: Whitespace-only text nodes between tags are dropped.

Cause: The tree builder skips text nodes containing only whitespace characters.

Rendering​

Nested Rounded Clips​

Symptom: When two nested elements both have overflow: hidden and border-radius, only the innermost clip's rounded corners are used.

Cause: Composing multiple rounded SDF clips requires shader-level intersection of two SDFs, which is not yet implemented. Rectangular scissor intersections work correctly.

Animated Image Frames​

Symptom: Animated GIF/WebP images may not advance frames in some engine configurations.

Cause: Frame selection uses a process-wide clock anchor that relies on the host calling render_frame on each frame tick. If the host throttles rendering, animation frame rates are affected.

Interactivity​

Scroll Hit-Testing​

Symptom: Click coordinates inside a scroll container may not be correctly mapped to the scrolled content for hit-testing.

Cause: Element scroll offsets are applied at paint time but may not be subtracted from hit-test coordinates for all interactions. Viewport scrolling is handled; element-level scroll hit-testing is partial.

No <select> Dropdown​

Symptom: The <select> element renders as a static block with no interactive dropdown.

Cause: The popup menu rendering and interaction system for <select> is not yet implemented.

Form Validation Gaps​

Symptom: pattern (regex) validation is not implemented. type=email/type=url inputs don't validate format. minlength/maxlength not checked on <textarea>.

Cause: Regex engine not bundled. Type-specific validation rules not yet coded. Textarea constraints not wired.

Wheel Events on Element Callbacks​

Symptom: Mouse wheel events scroll the element but are not forwarded to element on_event callbacks.

Cause: Wheel events are consumed for scroll handling before callback dispatch on the focused element.

Performance​

Flex/Grid Incremental Relayout​

Symptom: Changing one child inside a flex or grid container causes the entire container to re-layout.

Cause: Flex and grid have cross-item dependencies (free space redistribution, track sizing). Incremental layout falls back to full re-layout for these container types.

First Frame Latency​

Symptom: The first frame after loading a large document or many images may have higher latency.

Cause: Image loading and font rasterization happen on first use. Preload with tree.preload_asset() to mitigate.