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Status

This page documents the implementation status of various HTML and CSS features in Blitz.

CSS PropertiesHTML ElementsEventsWPT Tests

This page documents Blitz's scores on the "css" subsuite of the Web Platform Tests.

Note: As it does not have a JavaScript engine, Blitz can only run about 20% of the total subtests. In the numbers below, tests that Blitz can't run are ignored and percentages are relative to the number of tests run.

Data from commit:
708eb61 WPT runner: support mismatch reftests and multiple rel=match links (#665) (2026-08-09)

wpt / css / css-position

AreaInterop ScoreTestsTest %SubtestsSubtest %
Total20.10%(51/256)19.92%(61/298)20.47%
crashtests100.00%(1/1)100.00%(1/1)100.00%
multicol0.00%(0/16)0.00%(0/16)0.00%
overlay50.00%(4/8)50.00%(4/8)50.00%
static-position11.10%(4/36)11.11%(4/36)11.11%
sticky18.40%(14/76)18.42%(14/76)18.42%
TestSubtestsSubtest %Status
absolute-pos-box-inside-fixed-pos-box-with-changing-height.html(0/1)0.00%FAIL
backdrop-inherit-rendered.html(1/1)100.00%PASS
block-axis-constraint-changes-for-out-of-flow-box.html(0/1)0.00%FAIL
change-insets-inside-strict-containment-nested.html(0/1)0.00%FAIL
containing-block-change-button.html(0/1)0.00%FAIL
containing-block-change-scrollframe.html(0/1)0.00%FAIL
fixed-z-index-blend.html(1/1)100.00%PASS
hypothetical-box-scroll-parent.html(0/1)0.00%FAIL
hypothetical-box-scroll-viewport.html(0/1)0.00%FAIL
hypothetical-dynamic-change-001.html(0/1)0.00%FAIL
hypothetical-dynamic-change-002.html(0/1)0.00%FAIL
hypothetical-dynamic-change-003.html(0/1)0.00%FAIL
invalidate-opacity-negative-z-index.html(0/1)0.00%FAIL
nested-inline-abspos-child-with-siblings.html(1/1)100.00%PASS
nested-inline-abspos-child.html(1/1)100.00%PASS
position-absolute-center-001.html(0/1)0.00%FAIL
position-absolute-center-002.html(0/1)0.00%FAIL
position-absolute-center-003.html(0/1)0.00%FAIL
position-absolute-center-004.html(0/1)0.00%FAIL
position-absolute-center-006.html(0/1)0.00%FAIL
position-absolute-center-007.html(0/1)0.00%FAIL
position-absolute-dynamic-auto-overflow.html(0/1)0.00%FAIL
position-absolute-dynamic-list-marker.html(0/1)0.00%FAIL
position-absolute-dynamic-overflow-001.html(1/1)100.00%PASS
position-absolute-dynamic-overflow-002.html(1/1)100.00%PASS
position-absolute-dynamic-relayout-001.html(0/1)0.00%FAIL
position-absolute-dynamic-relayout-002.html(0/1)0.00%FAIL
position-absolute-dynamic-relayout-003.html(1/1)100.00%PASS
position-absolute-dynamic-relayout-004.html(0/1)0.00%FAIL
position-absolute-dynamic-relayout-005.html(0/1)0.00%FAIL
position-absolute-dynamic-relayout-006.html(0/1)0.00%FAIL
position-absolute-dynamic-relayout-007.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-flex.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-floats-001.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-floats-002.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-floats-003.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-floats-004.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-inline.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-margin-001.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-margin-002.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position-table-cell.html(0/1)0.00%FAIL
position-absolute-dynamic-static-position.html(0/1)0.00%FAIL
position-absolute-fieldset.html(1/1)100.00%PASS
position-absolute-fit-content-auto-margin.html(0/1)0.00%FAIL
position-absolute-fit-content.html(0/1)0.00%FAIL
position-absolute-iframe-print-001.sub.html(0/1)0.00%FAIL
position-absolute-iframe-print-002.sub.html(0/1)0.00%FAIL
position-absolute-in-inline-003.html(0/1)0.00%FAIL
position-absolute-in-inline-004.html(0/1)0.00%FAIL
position-absolute-in-inline-005.html(0/1)0.00%FAIL
position-absolute-in-inline-006.html(0/1)0.00%FAIL
position-absolute-in-inline-007a.html(0/1)0.00%FAIL
position-absolute-in-inline-007b.html(0/1)0.00%FAIL
position-absolute-in-inline-008a.html(0/1)0.00%FAIL
position-absolute-in-inline-008b.html(0/1)0.00%FAIL
position-absolute-in-inline-009.html(0/1)0.00%FAIL
position-absolute-in-inline-010.html(0/1)0.00%FAIL
position-absolute-in-inline-011.html(0/1)0.00%FAIL
position-absolute-in-inline-012.html(0/1)0.00%FAIL
position-absolute-in-inline-margin-top.html(1/1)100.00%PASS
position-absolute-large-negative-inset.html(1/1)100.00%PASS
position-absolute-margin-auto-001.html(0/1)0.00%FAIL
position-absolute-multicol-001.html(1/1)100.00%PASS
position-absolute-replaced-intrinsic-size.tentative.html(1/1)100.00%PASS
position-absolute-replaced-no-intrinsic-size.tentative.html(0/1)0.00%FAIL
position-absolute-replaced-with-display-table.html(1/1)100.00%PASS
position-absolute-root-element-flex.html(0/1)0.00%FAIL
position-absolute-root-element-grid.html(0/1)0.00%FAIL
position-absolute-scrollable-overflow-001.html(8/14)57.14%FAIL
position-absolute-scrollable-overflow-zero.html(1/1)100.00%PASS
position-absolute-semi-replaced-stretch-button.html(1/1)100.00%PASS
position-absolute-semi-replaced-stretch-input.html(1/1)100.00%PASS
position-absolute-semi-replaced-stretch-other.html(1/1)100.00%PASS
position-absolute-under-non-containing-stacking-context.html(1/1)100.00%PASS
position-absolute-with-negative-sized-imcb.html(2/30)6.67%FAIL
position-change.html(1/1)100.00%PASS
position-fixed-dynamic-transformed-sibling.html(0/1)0.00%FAIL
position-fixed-overflow-print.html(0/1)0.00%FAIL
position-fixed-root-element-flex.html(0/1)0.00%FAIL
position-fixed-root-element-grid.html(0/1)0.00%FAIL
position-fixed-scroll-nested-fixed.html(0/1)0.00%FAIL
position-fixed-scroll-overlap.html(1/1)100.00%PASS
position-fixed-video-controls-print.html(1/1)100.00%PASS
position-relative-001.html(0/1)0.00%FAIL
position-relative-002.html(0/1)0.00%FAIL
position-relative-003.html(1/1)100.00%PASS
position-relative-004.html(1/1)100.00%PASS
position-relative-005.html(1/1)100.00%PASS
position-relative-006.html(1/1)100.00%PASS
position-relative-007.html(0/1)0.00%FAIL
position-relative-008.html(1/1)100.00%PASS
position-relative-009.html(1/1)100.00%PASS
position-relative-010.html(0/1)0.00%FAIL
position-relative-011.html(0/1)0.00%FAIL
position-relative-012.html(0/1)0.00%FAIL
position-relative-013.html(0/1)0.00%FAIL
position-relative-014.html(0/1)0.00%FAIL
position-relative-table-caption.html(0/1)0.00%FAIL
position-relative-table-tbody-left-absolute-child.html(0/1)0.00%FAIL
position-relative-table-tbody-left.html(0/1)0.00%FAIL
position-relative-table-tbody-top-absolute-child.html(0/1)0.00%FAIL
position-relative-table-tbody-top.html(0/1)0.00%FAIL
position-relative-table-td-left.html(0/1)0.00%FAIL
position-relative-table-td-top.html(0/1)0.00%FAIL
position-relative-table-tfoot-left-absolute-child.html(0/1)0.00%FAIL
position-relative-table-tfoot-left.html(0/1)0.00%FAIL
position-relative-table-tfoot-top-absolute-child.html(0/1)0.00%FAIL
position-relative-table-tfoot-top.html(0/1)0.00%FAIL
position-relative-table-thead-left-absolute-child.html(0/1)0.00%FAIL
position-relative-table-thead-left.html(0/1)0.00%FAIL
position-relative-table-thead-top-absolute-child.html(0/1)0.00%FAIL
position-relative-table-thead-top.html(0/1)0.00%FAIL
position-relative-table-tr-left-absolute-child.html(0/1)0.00%FAIL
position-relative-table-tr-left.html(0/1)0.00%FAIL
position-relative-table-tr-top-absolute-child.html(0/1)0.00%FAIL
position-relative-table-tr-top.html(0/1)0.00%FAIL
position-static-001.html(0/1)0.00%FAIL
replaced-object-backdrop.html(0/1)0.00%FAIL
z-index-blend-will-change-overlapping-layers.html(1/1)100.00%PASS