Status
This page documents the implementation status of various HTML and CSS features in Blitz.
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:
1b044c2 Use warpbuild runner for WPT tests (#905) (2026-09-16)
| Area | Interop Score | Tests | Test % | Subtests | Subtest % |
|---|---|---|---|---|---|
| Total | 49.20% | (15843/33550) | 47.22% | (105497/194360) | 54.28% |
| CSS2 | 66.60% | (4237/6365) | 66.57% | (6438/8805) | 73.12% |
| WOFF2 | 98.30% | (293/298) | 98.32% | (293/298) | 98.32% |
| compositing | 30.60% | (24/81) | 29.63% | (156/219) | 71.23% |
| css-align | 59.80% | (135/296) | 45.61% | (3813/5364) | 71.09% |
| css-anchor-position | 18.20% | (81/522) | 15.52% | (3483/13894) | 25.07% |
| css-animations | 56.50% | (103/194) | 53.09% | (813/1454) | 55.91% |
| css-backgrounds | 68.30% | (552/848) | 65.09% | (5051/6908) | 73.12% |
| css-borders | 30.50% | (50/174) | 28.74% | (1001/1651) | 60.63% |
| css-box | 32.10% | (31/147) | 21.09% | (691/1124) | 61.48% |
| css-break | 21.70% | (269/1252) | 21.49% | (324/1917) | 16.90% |
| css-cascade | 58.20% | (72/133) | 54.14% | (756/1035) | 73.04% |
| css-color | 87.80% | (310/373) | 83.11% | (11211/12937) | 86.66% |
| css-color-adjust | 44.20% | (13/34) | 38.24% | (135/176) | 76.70% |
| css-color-hdr | 14.60% | (0/4) | 0.00% | (17/116) | 14.66% |
| css-conditional | 43.00% | (190/461) | 41.21% | (1852/2297) | 80.63% |
| css-contain | 54.20% | (305/576) | 52.95% | (450/961) | 46.83% |
| css-content | 19.50% | (13/78) | 16.67% | (193/322) | 59.94% |
| css-counter-styles | 5.60% | (9/252) | 3.57% | (75/395) | 18.99% |
| css-device-adapt | 28.50% | (2/7) | 28.57% | (2/7) | 28.57% |
| css-display | 42.30% | (100/246) | 40.65% | (349/657) | 53.12% |
| css-easing | 73.40% | (8/14) | 57.14% | (116/158) | 73.42% |
| css-env | 94.60% | (9/11) | 81.82% | (48/53) | 90.57% |
| css-exclusions | 0.00% | (0/12) | 0.00% | (0/15) | 0.00% |
| css-flexbox | 77.20% | (1048/1406) | 74.54% | (4027/5759) | 69.93% |
| css-font-loading | 19.60% | (6/31) | 19.35% | (19/237) | 8.02% |
| css-fonts | 56.10% | (273/542) | 50.37% | (6532/8828) | 73.99% |
| css-forced-color-adjust | 83.30% | (2/4) | 50.00% | (12/14) | 85.71% |
| css-forms | 8.60% | (2/23) | 8.70% | (2/81) | 2.47% |
| css-gaps | 9.30% | (47/527) | 8.92% | (366/4600) | 7.96% |
| css-grid | 41.50% | (906/2348) | 38.59% | (8276/16466) | 50.26% |
| css-highlight-api | 11.50% | (15/133) | 11.28% | (23/210) | 10.95% |
| css-image-animation | 68.10% | (15/22) | 68.18% | (15/22) | 68.18% |
| css-images | 31.90% | (154/507) | 30.37% | (3498/4053) | 86.31% |
| css-inline | 22.20% | (49/246) | 19.92% | (295/1040) | 28.37% |
| css-layout-api | 13.10% | (19/153) | 12.42% | (23/159) | 14.47% |
| css-link-params | 25.00% | (1/4) | 25.00% | (12/26) | 46.15% |
| css-lists | 42.60% | (89/222) | 40.09% | (790/1157) | 68.28% |
| css-logical | 74.90% | (54/90) | 60.00% | (877/1341) | 65.40% |
| css-masking | 42.10% | (222/558) | 39.78% | (3738/6884) | 54.30% |
| css-mixins | 10.20% | (1/53) | 1.89% | (66/601) | 10.98% |
| css-motion-path | 100.00% | (1/1) | 100.00% | (1/1) | 100.00% |
| css-multicol | 40.40% | (287/722) | 39.75% | (869/2244) | 38.73% |
| css-namespaces | 100.00% | (23/23) | 100.00% | (23/23) | 100.00% |
| css-navigation | 25.40% | (4/26) | 15.38% | (30/88) | 34.09% |
| css-nesting | 77.90% | (32/45) | 71.11% | (111/140) | 79.29% |
| css-overflow | 30.50% | (227/785) | 28.92% | (622/1669) | 37.27% |
| css-overscroll-behavior | 59.50% | (2/7) | 28.57% | (58/82) | 70.73% |
| css-page | 39.00% | (100/258) | 38.76% | (112/333) | 33.63% |
| css-paint-api | 81.30% | (95/118) | 80.51% | (114/137) | 83.21% |
| css-parser-api | 7.00% | (0/1) | 0.00% | (5/71) | 7.04% |
| css-position | 41.40% | (148/381) | 38.85% | (1024/1711) | 59.85% |
| css-properties-values-api | 33.50% | (35/124) | 28.23% | (535/1054) | 50.76% |
| css-pseudo | 35.10% | (118/341) | 34.60% | (184/1072) | 17.16% |
| css-rhythm | 25.50% | (8/35) | 22.86% | (71/201) | 35.32% |
| css-ruby | 39.80% | (71/178) | 39.89% | (99/247) | 40.08% |
| css-scroll-anchoring | 12.60% | (8/63) | 12.70% | (9/83) | 10.84% |
| css-scroll-snap | 13.10% | (17/151) | 11.26% | (157/741) | 21.19% |
| css-scrollbars | 44.10% | (22/57) | 38.60% | (67/115) | 58.26% |
| css-shadow | 7.10% | (14/206) | 6.80% | (24/396) | 6.06% |
| css-shapes | 17.40% | (65/381) | 17.06% | (709/7751) | 9.15% |
| css-size-adjust | 20.00% | (1/5) | 20.00% | (4/215) | 1.86% |
| css-sizing | 54.30% | (374/747) | 50.07% | (3719/6415) | 57.97% |
| css-style-attr | 93.70% | (15/16) | 93.75% | (15/16) | 93.75% |
| css-syntax | 63.50% | (25/44) | 56.82% | (404/433) | 93.30% |
| css-tables | 53.60% | (160/340) | 47.06% | (560/1104) | 50.72% |
| css-text | 54.50% | (1017/1891) | 53.78% | (3475/6049) | 57.45% |
| css-text-decor | 37.90% | (132/364) | 36.26% | (1112/1692) | 65.72% |
| css-transforms | 51.80% | (457/926) | 49.35% | (3946/6333) | 62.31% |
| css-transitions | 54.10% | (54/114) | 47.37% | (863/1338) | 64.50% |
| css-typed-om | 3.70% | (13/373) | 3.49% | (48/1283) | 3.74% |
| css-ui | 89.80% | (944/1068) | 88.39% | (2171/2876) | 75.49% |
| css-values | 61.20% | (280/507) | 55.23% | (5570/10527) | 52.91% |
| css-variables | 94.00% | (211/235) | 89.79% | (596/739) | 80.65% |
| css-view-transitions | 10.20% | (50/490) | 10.20% | (124/1643) | 7.55% |
| css-viewport | 74.30% | (97/135) | 71.85% | (305/412) | 74.03% |
| css-will-change | 49.00% | (26/53) | 49.06% | (194/221) | 87.78% |
| css-writing-modes | 16.30% | (196/1229) | 15.95% | (275/1458) | 18.86% |
| css-zoom | 100.00% | (1/1) | 100.00% | (1/1) | 100.00% |
| cssom | 50.80% | (86/210) | 40.95% | (2792/4017) | 69.50% |
| cssom-view | 35.30% | (59/210) | 28.10% | (769/1863) | 41.28% |
| fetching | 0.00% | (0/1) | 0.00% | (0/4) | 0.00% |
| fill-stroke | 22.10% | (2/11) | 18.18% | (94/410) | 22.93% |
| filter-effects | 49.20% | (182/392) | 46.43% | (1758/3308) | 53.14% |
| geometry | 96.20% | (25/27) | 92.59% | (1085/1088) | 99.72% |
| mediaqueries | 52.10% | (48/92) | 52.17% | (48/455) | 10.55% |
| motion | 17.50% | (14/148) | 9.46% | (2475/5061) | 48.90% |
| printing | 77.40% | (24/31) | 77.42% | (24/31) | 77.42% |
| reference | 66.60% | (2/3) | 66.67% | (2/3) | 66.67% |
| selectors | 51.80% | (362/737) | 49.12% | (2406/4965) | 48.46% |