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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:
1093b86 wpt: skip non-UTF-8 test files instead of crashing (#659) (2026-08-09)

wpt / css / css-backgrounds

AreaInterop ScoreTestsTest %SubtestsSubtest %
Total36.50%(261/714)36.55%(261/714)36.55%
animations41.80%(18/43)41.86%(18/43)41.86%
background-attachment-local0.00%(0/17)0.00%(0/17)0.00%
background-clip24.00%(12/50)24.00%(12/50)24.00%
background-origin41.60%(5/12)41.67%(5/12)41.67%
background-position66.60%(2/3)66.67%(2/3)66.67%
background-repeat87.50%(7/8)87.50%(7/8)87.50%
background-size5.50%(12/217)5.53%(12/217)5.53%
box-shadow0.00%(0/7)0.00%(0/7)0.00%
crashtests100.00%(2/2)100.00%(2/2)100.00%
hidpi0.00%(0/1)0.00%(0/1)0.00%
TestSubtestsSubtest %Status
background-334.html(1/1)100.00%PASS
background-attachment-350.html(0/1)0.00%FAIL
background-attachment-353.html(0/1)0.00%FAIL
background-attachment-fixed-block-002.html(1/1)100.00%PASS
background-attachment-fixed-border-radius-offset.html(0/1)0.00%FAIL
background-attachment-fixed-inline-002.html(1/1)100.00%PASS
background-attachment-fixed-inline-scrolled.html(1/1)100.00%PASS
background-attachment-fixed-inside-transform-1.html(1/1)100.00%PASS
background-attachment-local-block-002.html(1/1)100.00%PASS
background-attachment-local-hidden.html(0/1)0.00%FAIL
background-attachment-local-inline-002.html(1/1)100.00%PASS
background-attachment-margin-root-001.html(0/1)0.00%FAIL
background-attachment-margin-root-002.html(0/1)0.00%FAIL
background-clip-002.html(1/1)100.00%PASS
background-clip-003.html(1/1)100.00%PASS
background-clip-004.html(1/1)100.00%PASS
background-clip-005.html(1/1)100.00%PASS
background-clip-006.html(1/1)100.00%PASS
background-clip-007.html(1/1)100.00%PASS
background-clip-008.html(1/1)100.00%PASS
background-clip-009.html(1/1)100.00%PASS
background-clip-010.html(1/1)100.00%PASS
background-clip-border-area-and-blend-mode.html(0/1)0.00%FAIL
background-clip-color-repaint.html(0/1)0.00%FAIL
background-clip-color.html(1/1)100.00%PASS
background-clip-content-box-001.html(1/1)100.00%PASS
background-clip-content-box-002.html(1/1)100.00%PASS
background-clip-content-box-with-border-radius-002.html(0/1)0.00%FAIL
background-clip-content-box-with-border-radius-003.html(0/1)0.00%FAIL
background-clip-padding-box-001.html(1/1)100.00%PASS
background-clip-padding-box-with-border-radius-002.html(0/1)0.00%FAIL
background-clip-padding-box-with-border-radius-003.html(0/1)0.00%FAIL
background-clip-padding-box-with-border-radius.html(1/1)100.00%PASS
background-clip-text-and-blend-mode.html(0/1)0.00%FAIL
background-clip_padding-box.html(1/1)100.00%PASS
background-color-body-propagation-001.html(1/1)100.00%PASS
background-color-body-propagation-002.html(1/1)100.00%PASS
background-color-body-propagation-003.html(0/1)0.00%FAIL
background-color-body-propagation-004.html(0/1)0.00%FAIL
background-color-body-propagation-005.html(1/1)100.00%PASS
background-color-body-propagation-006.html(0/1)0.00%FAIL
background-color-body-propagation-007.html(0/1)0.00%FAIL
background-color-body-propagation-008.html(0/1)0.00%FAIL
background-color-body-propagation-009.html(0/1)0.00%FAIL
background-color-body-propagation-010.html(1/1)100.00%PASS
background-color-clip.html(1/1)100.00%PASS
background-color-root-propagation-001.html(0/1)0.00%FAIL
background-color-root-propagation-002.html(0/1)0.00%FAIL
background-color-root-propagation-003.html(1/1)100.00%PASS
background-gradient-interpolation-003.html(0/1)0.00%FAIL
background-gradient-subpixel-fills-area.html(1/1)100.00%PASS
background-image-001.html(1/1)100.00%PASS
background-image-002.html(1/1)100.00%PASS
background-image-003.html(1/1)100.00%PASS
background-image-004.html(1/1)100.00%PASS
background-image-005.html(1/1)100.00%PASS
background-image-006.html(1/1)100.00%PASS
background-image-007.html(0/1)0.00%FAIL
background-image-centered-with-border-radius.html(1/1)100.00%PASS
background-image-centered.html(1/1)100.00%PASS
background-image-cover-zoomed-1.html(1/1)100.00%PASS
background-image-first-letter.html(1/1)100.00%PASS
background-image-first-line.html(0/1)0.00%FAIL
background-image-gradient-currentcolor-conic-repaint.html(0/1)0.00%FAIL
background-image-gradient-currentcolor-linear-repaint.html(0/1)0.00%FAIL
background-image-gradient-currentcolor-radial-repaint.html(0/1)0.00%FAIL
background-image-gradient-currentcolor-visited.html(0/1)0.00%FAIL
background-image-gradient-interpolation-repaint.html(1/1)100.00%PASS
background-image-large-with-auto.html(1/1)100.00%PASS
background-image-none-gradient-repaint.html(0/1)0.00%FAIL
background-image-shared-stylesheet.html(0/1)0.00%FAIL
background-image-table-cells-straddling-no-repeat.html(0/1)0.00%FAIL
background-image-table-cells-zoomed.html(1/1)100.00%PASS
background-image-with-border-radius-fidelity.html(1/1)100.00%PASS
background-margin-iframe-root.html(1/1)100.00%PASS
background-margin-root.html(0/1)0.00%FAIL
background-margin-transformed-root.html(0/1)0.00%FAIL
background-margin-will-change-root.html(0/1)0.00%FAIL
background-multiple-layers-table-cell.html(0/1)0.00%FAIL
background-none-none-and-color.html(1/1)100.00%PASS
background-origin-002.html(1/1)100.00%PASS
background-origin-003.html(1/1)100.00%PASS
background-origin-004.html(1/1)100.00%PASS
background-origin-005.html(1/1)100.00%PASS
background-origin-006.html(0/1)0.00%FAIL
background-origin-007.html(1/1)100.00%PASS
background-origin-008.html(1/1)100.00%PASS
background-paint-order-001.html(1/1)100.00%PASS
background-position-calc-minmax-001.html(1/1)100.00%PASS
background-position-negative-percentage-comparison-002.html(1/1)100.00%PASS
background-position-negative-percentage-comparison.html(1/1)100.00%PASS
background-position-subpixel-at-border.tentative.html(0/1)0.00%FAIL
background-position-three-four-values.html(1/1)100.00%PASS
background-position-xy-three-four-values-passthru.html(1/1)100.00%PASS
background-repeat-round-1a.html(1/1)100.00%PASS
background-repeat-round-1b.html(1/1)100.00%PASS
background-repeat-round-1c.html(1/1)100.00%PASS
background-repeat-round-1d.html(1/1)100.00%PASS
background-repeat-round-1e.html(1/1)100.00%PASS
background-repeat-round-2.html(0/1)0.00%FAIL
background-repeat-round-3.html(1/1)100.00%PASS
background-repeat-round-4.html(1/1)100.00%PASS
background-repeat-round-empty-crash.html(1/1)100.00%PASS
background-repeat-space-10.html(1/1)100.00%PASS
background-repeat-space-1a.html(1/1)100.00%PASS
background-repeat-space-1b.html(1/1)100.00%PASS
background-repeat-space-1c.html(1/1)100.00%PASS
background-repeat-space-2.html(1/1)100.00%PASS
background-repeat-space-3.html(1/1)100.00%PASS
background-repeat-space-4.html(1/1)100.00%PASS
background-repeat-space-5.html(1/1)100.00%PASS
background-repeat-space-6.html(1/1)100.00%PASS
background-repeat-space-7.html(1/1)100.00%PASS
background-repeat-space-8.html(1/1)100.00%PASS
background-repeat-space-9.html(1/1)100.00%PASS
background-rounded-image-clip-001.html(0/1)0.00%FAIL
background-rounded-image-clip-002.html(1/1)100.00%PASS
background-size-002.html(1/1)100.00%PASS
background-size-005.html(1/1)100.00%PASS
background-size-006.html(1/1)100.00%PASS
background-size-007.html(1/1)100.00%PASS
background-size-008.html(1/1)100.00%PASS
background-size-009.html(1/1)100.00%PASS
background-size-010.html(1/1)100.00%PASS
background-size-011.html(1/1)100.00%PASS
background-size-012.html(1/1)100.00%PASS
background-size-013.html(1/1)100.00%PASS
background-size-014.html(1/1)100.00%PASS
background-size-015.html(1/1)100.00%PASS
background-size-016.html(1/1)100.00%PASS
background-size-017.html(1/1)100.00%PASS
background-size-018.html(1/1)100.00%PASS
background-size-019.html(1/1)100.00%PASS
background-size-020.html(1/1)100.00%PASS
background-size-021.html(1/1)100.00%PASS
background-size-025.html(0/1)0.00%FAIL
background-size-026.html(1/1)100.00%PASS
background-size-027.html(1/1)100.00%PASS
background-size-028.html(1/1)100.00%PASS
background-size-029.html(0/1)0.00%FAIL
background-size-030.html(1/1)100.00%PASS
background-size-031.html(1/1)100.00%PASS
background-size-034.html(1/1)100.00%PASS
background-size-041.html(1/1)100.00%PASS
background-size-042.html(1/1)100.00%PASS
background-size-043.html(0/1)0.00%FAIL
background-size-044.html(0/1)0.00%FAIL
background-size-contain-001.html(1/1)100.00%PASS
background-size-contain-002.html(1/1)100.00%PASS
background-size-cover-001.html(1/1)100.00%PASS
background-size-cover-002.html(1/1)100.00%PASS
background-size-cover-003.html(1/1)100.00%PASS
background-size-one-value-1x1-image.html(1/1)100.00%PASS
background-size-percentage-root.html(0/1)0.00%FAIL
background-size-with-negative-value.html(1/1)100.00%PASS
bg-color-with-gradient.html(0/1)0.00%FAIL
border-bottom-left-radius-001.xht(1/1)100.00%PASS
border-bottom-left-radius-004.xht(1/1)100.00%PASS
border-bottom-left-radius-005.xht(1/1)100.00%PASS
border-bottom-left-radius-010.xht(1/1)100.00%PASS
border-bottom-left-radius-011.xht(1/1)100.00%PASS
border-bottom-left-radius-014.xht(1/1)100.00%PASS
border-bottom-right-radius-001.xht(1/1)100.00%PASS
border-bottom-right-radius-004.xht(1/1)100.00%PASS
border-bottom-right-radius-005.xht(1/1)100.00%PASS
border-bottom-right-radius-010.xht(1/1)100.00%PASS
border-bottom-right-radius-011.xht(1/1)100.00%PASS
border-bottom-right-radius-014.xht(1/1)100.00%PASS
border-bottom-width-medium.html(1/1)100.00%PASS
border-bottom-width-thick.html(1/1)100.00%PASS
border-bottom-width-thin.html(1/1)100.00%PASS
border-image-002.html(0/1)0.00%FAIL
border-image-003.html(0/1)0.00%FAIL
border-image-004.html(0/1)0.00%FAIL
border-image-006.html(0/1)0.00%FAIL
border-image-007.html(0/1)0.00%FAIL
border-image-011.html(0/1)0.00%FAIL
border-image-012.html(0/1)0.00%FAIL
border-image-013.html(0/1)0.00%FAIL
border-image-017.xht(0/1)0.00%FAIL
border-image-018.xht(0/1)0.00%FAIL
border-image-019.xht(0/1)0.00%FAIL
border-image-020.xht(0/1)0.00%FAIL
border-image-021.html(0/1)0.00%FAIL
border-image-calc.html(0/1)0.00%FAIL
border-image-displayed-with-transparent-border-color.html(0/1)0.00%FAIL
border-image-image-type-001.htm(1/1)100.00%PASS
border-image-image-type-002.htm(1/1)100.00%PASS
border-image-image-type-003.htm(0/1)0.00%FAIL
border-image-image-type-004.htm(1/1)100.00%PASS
border-image-image-type-005.htm(1/1)100.00%PASS
border-image-outset-003.html(0/1)0.00%FAIL
border-image-outset-004.html(0/1)0.00%FAIL
border-image-repeat-002.htm(0/1)0.00%FAIL
border-image-repeat-004.htm(0/1)0.00%FAIL
border-image-repeat-005.html(0/1)0.00%FAIL
border-image-repeat-1.html(0/1)0.00%FAIL
border-image-repeat-repeat-001.html(0/1)0.00%FAIL
border-image-repeat-round-003.html(0/1)0.00%FAIL
border-image-repeat-round-1.html(0/1)0.00%FAIL
border-image-repeat-round-2.html(0/1)0.00%FAIL
border-image-repeat-round-stretch-001.html(0/1)0.00%FAIL
border-image-repeat-round.html(0/1)0.00%FAIL
border-image-repeat-space-011.html(0/1)0.00%FAIL
border-image-repeat-space-1.html(0/1)0.00%FAIL
border-image-repeat-space-10.html(0/1)0.00%FAIL
border-image-repeat-space-2.html(0/1)0.00%FAIL
border-image-repeat-space-3.html(0/1)0.00%FAIL
border-image-repeat-space-4-ref-1.html(0/1)0.00%FAIL
border-image-repeat-space-4.html(0/1)0.00%FAIL
border-image-repeat-space-5-ref-1.html(0/1)0.00%FAIL
border-image-repeat-space-5.html(0/1)0.00%FAIL
border-image-repeat-space-6.html(0/1)0.00%FAIL
border-image-repeat-space-7.html(0/1)0.00%FAIL
border-image-repeat-space-8.html(1/1)100.00%PASS
border-image-repeat-space-9.html(1/1)100.00%PASS
border-image-repeat-stretch-round-001.html(0/1)0.00%FAIL
border-image-round-and-stretch.html(0/1)0.00%FAIL
border-image-shorthand-001.htm(1/1)100.00%PASS
border-image-shorthand-002.htm(0/1)0.00%FAIL
border-image-shorthand-003.htm(0/1)0.00%FAIL
border-image-slice-001.xht(0/1)0.00%FAIL
border-image-slice-002.xht(0/1)0.00%FAIL
border-image-slice-003.xht(1/1)100.00%PASS
border-image-slice-004.htm(0/1)0.00%FAIL
border-image-slice-005.htm(0/1)0.00%FAIL
border-image-slice-006.htm(0/1)0.00%FAIL
border-image-slice-007.htm(0/1)0.00%FAIL
border-image-slice-fill-001.html(0/1)0.00%FAIL
border-image-slice-fill-002.html(0/1)0.00%FAIL
border-image-slice-fill-003.html(0/1)0.00%FAIL
border-image-slice-percentage.html(0/1)0.00%FAIL
border-image-space-001.html(0/1)0.00%FAIL
border-image-width-001.htm(0/1)0.00%FAIL
border-image-width-005.xht(0/1)0.00%FAIL
border-image-width-006.xht(0/1)0.00%FAIL
border-image-width-007.xht(0/1)0.00%FAIL
border-image-width-008.html(0/1)0.00%FAIL
border-image-width-009.html(0/1)0.00%FAIL
border-image-width-should-extend-to-padding.html(0/1)0.00%FAIL
border-left-width-medium.html(0/1)0.00%FAIL
border-left-width-thick.html(0/1)0.00%FAIL
border-left-width-thin.html(0/1)0.00%FAIL
border-radius-001.xht(1/1)100.00%PASS
border-radius-002.xht(1/1)100.00%PASS
border-radius-003.xht(1/1)100.00%PASS
border-radius-004.xht(1/1)100.00%PASS
border-radius-005.xht(1/1)100.00%PASS
border-radius-006.xht(1/1)100.00%PASS
border-radius-007.xht(1/1)100.00%PASS
border-radius-008.xht(1/1)100.00%PASS
border-radius-009.xht(1/1)100.00%PASS
border-radius-010.xht(1/1)100.00%PASS
border-radius-011.xht(1/1)100.00%PASS
border-radius-012.html(1/1)100.00%PASS
border-radius-013.html(1/1)100.00%PASS
border-radius-clip-001.html(0/1)0.00%FAIL
border-radius-clip-002.htm(1/1)100.00%PASS
border-radius-clipping-002.html(0/1)0.00%FAIL
border-radius-clipping-with-transform-001.html(1/1)100.00%PASS
border-radius-dynamic-from-no-radius.html(0/1)0.00%FAIL
border-radius-horizontal-value-is-zero.html(1/1)100.00%PASS
border-radius-shorthand-002.html(1/1)100.00%PASS
border-right-width-medium.html(0/1)0.00%FAIL
border-right-width-thick.html(0/1)0.00%FAIL
border-right-width-thin.html(0/1)0.00%FAIL
border-top-left-radius-001.xht(1/1)100.00%PASS
border-top-left-radius-004.xht(1/1)100.00%PASS
border-top-left-radius-005.xht(1/1)100.00%PASS
border-top-left-radius-010.xht(1/1)100.00%PASS
border-top-left-radius-011.xht(1/1)100.00%PASS
border-top-left-radius-014.xht(1/1)100.00%PASS
border-top-right-radius-001.xht(1/1)100.00%PASS
border-top-right-radius-004.xht(1/1)100.00%PASS
border-top-right-radius-005.xht(1/1)100.00%PASS
border-top-right-radius-010.xht(1/1)100.00%PASS
border-top-right-radius-011.xht(1/1)100.00%PASS
border-top-right-radius-014.xht(1/1)100.00%PASS
border-top-width-medium.html(1/1)100.00%PASS
border-top-width-thick.html(1/1)100.00%PASS
border-top-width-thin.html(1/1)100.00%PASS
border-width-pixel-snapping-001-b.html(1/1)100.00%PASS
box-shadow-005.html(1/1)100.00%PASS
box-shadow-029.html(1/1)100.00%PASS
box-shadow-039.html(1/1)100.00%PASS
box-shadow-040.html(1/1)100.00%PASS
box-shadow-041.html(0/1)0.00%FAIL
box-shadow-042.html(0/1)0.00%FAIL
box-shadow-body.html(1/1)100.00%PASS
box-shadow-border-radius-001.html(0/1)0.00%FAIL
box-shadow-calc.html(1/1)100.00%PASS
box-shadow-currentcolor.html(1/1)100.00%PASS
box-shadow-inset-without-border-radius.html(0/1)0.00%FAIL
box-shadow-invalid-001.html(1/1)100.00%PASS
box-shadow-multiple-001.html(0/1)0.00%FAIL
box-shadow-outset-without-border-radius-001.html(0/1)0.00%FAIL
box-shadow-overlapping-001.html(0/1)0.00%FAIL
box-shadow-overlapping-002.html(1/1)100.00%PASS
box-shadow-overlapping-003.html(1/1)100.00%PASS
box-shadow-overlapping-004.html(1/1)100.00%PASS
box-shadow-radius-000.html(0/1)0.00%FAIL
box-shadow-radius-001.html(0/1)0.00%FAIL
box-shadow-radius-002.html(0/1)0.00%FAIL
box-shadow-radius-generated.html(1/1)100.00%PASS
box-shadow-svg-root-fixed-position.html(1/1)100.00%PASS
box-shadow-table-border-collapse-001.html(0/1)0.00%FAIL
box-shadow-table-row-display.html(0/1)0.00%FAIL
child-move-reveals-parent-background.html(0/1)0.00%FAIL
color-mix-currentcolor-background-repaint-parent.html(0/1)0.00%FAIL
color-mix-currentcolor-background-repaint.html(0/1)0.00%FAIL
color-mix-currentcolor-border-repaint-parent.html(0/1)0.00%FAIL
color-mix-currentcolor-border-repaint.html(0/1)0.00%FAIL
color-mix-currentcolor-outline-repaint-parent.html(0/1)0.00%FAIL
color-mix-currentcolor-outline-repaint.html(0/1)0.00%FAIL
css-border-radius-001.html(1/1)100.00%PASS
css-box-shadow-001.html(0/1)0.00%FAIL
css3-background-clip-border-box.html(1/1)100.00%PASS
css3-background-clip-content-box.html(1/1)100.00%PASS
css3-background-clip-padding-box.html(1/1)100.00%PASS
css3-background-clip.html(1/1)100.00%PASS
css3-background-origin-border-box.html(1/1)100.00%PASS
css3-background-origin-content-box.html(1/1)100.00%PASS
css3-background-origin-padding-box.html(1/1)100.00%PASS
css3-background-size-001.html(1/1)100.00%PASS
css3-background-size-contain.html(1/1)100.00%PASS
css3-background-size.html(1/1)100.00%PASS
css3-border-image-repeat-repeat.html(0/1)0.00%FAIL
css3-border-image-repeat-stretch.html(0/1)0.00%FAIL
css3-border-image-source.html(0/1)0.00%FAIL
css3-box-shadow.html(1/1)100.00%PASS
currentcolor-border-repaint-parent.html(0/1)0.00%FAIL
document-canvas-remove-body.html(0/1)0.00%FAIL
fieldset-inset-shadow.html(1/1)100.00%PASS
first-letter-space-not-selected.html(1/1)100.00%PASS
gradient-wrong-interpolation-crash.html(1/1)100.00%PASS
inline-background-rtl-001.html(1/1)100.00%PASS
inner-border-non-renderable.html(1/1)100.00%PASS
inset-box-shadow-scroll.html(1/1)100.00%PASS
inset-box-shadow-stacking-context-scroll.html(1/1)100.00%PASS
linear-gradient-calc-crash.html(1/1)100.00%PASS
linear-gradient-currentcolor-first-line.html(0/1)0.00%FAIL
local-attachment-content-box-scroll.html(0/1)0.00%FAIL
local-attachment-flex-column-reverse-scroll.html(0/1)0.00%FAIL
local-attachment-flex-row-reverse-scroll.html(0/1)0.00%FAIL
local-attachment-rtl-and-flex-row-reverse-scroll.html(0/1)0.00%FAIL
local-attachment-rtl-scroll.html(0/1)0.00%FAIL
order-of-images.htm(1/1)100.00%PASS
scroll-positioned-multiple-background-images.html(0/1)0.00%FAIL
subpixel-repeat-no-repeat-mix.html(0/1)0.00%FAIL
table-cell-background-local-002.html(0/1)0.00%FAIL
table-cell-background-local-003.html(0/1)0.00%FAIL
table-cell-background-local.html(1/1)100.00%PASS
tiny-foreignObject-double-border-radius-crash.html(1/1)100.00%PASS
ttwf-reftest-borderRadius.html(0/1)0.00%FAIL