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:
7767a6a WPT runner: add crashtest support (#666) (2026-08-09)
| Area | Interop Score | Tests | Test % | Subtests | Subtest % |
|---|---|---|---|---|---|
| Total | 45.70% | (11657/25715) | 45.33% | (15346/35027) | 43.81% |
| CSS2 | 61.20% | (3824/6247) | 61.21% | (3833/6274) | 61.09% |
| WOFF2 | 94.90% | (283/298) | 94.97% | (283/298) | 94.97% |
| compositing | 15.00% | (9/60) | 15.00% | (9/60) | 15.00% |
| css-align | 29.80% | (32/164) | 19.51% | (330/1704) | 19.37% |
| css-anchor-position | 17.10% | (39/240) | 16.25% | (56/310) | 18.06% |
| css-animations | 50.00% | (22/44) | 50.00% | (22/44) | 50.00% |
| css-backgrounds | 36.50% | (261/714) | 36.55% | (261/714) | 36.55% |
| css-borders | 27.00% | (23/85) | 27.06% | (23/85) | 27.06% |
| css-box | 9.20% | (7/109) | 6.42% | (23/227) | 10.13% |
| css-break | 19.60% | (219/1118) | 19.59% | (223/1123) | 19.86% |
| css-cascade | 64.50% | (35/55) | 63.64% | (43/70) | 61.43% |
| css-color | 90.50% | (277/306) | 90.52% | (277/306) | 90.52% |
| css-color-adjust | 25.00% | (5/20) | 25.00% | (5/20) | 25.00% |
| css-conditional | 73.60% | (137/186) | 73.66% | (137/186) | 73.66% |
| css-contain | 50.90% | (227/449) | 50.56% | (287/578) | 49.65% |
| css-content | 9.30% | (6/64) | 9.38% | (6/64) | 9.38% |
| css-counter-styles | 2.90% | (7/234) | 2.99% | (7/234) | 2.99% |
| css-display | 26.70% | (57/213) | 26.76% | (57/213) | 26.76% |
| css-easing | 100.00% | (5/5) | 100.00% | (29/29) | 100.00% |
| css-exclusions | 0.00% | (0/4) | 0.00% | (0/4) | 0.00% |
| css-flexbox | 66.40% | (799/1236) | 64.64% | (1996/3543) | 56.34% |
| css-font-loading | 40.00% | (2/5) | 40.00% | (2/5) | 40.00% |
| css-fonts | 52.10% | (173/332) | 52.11% | (173/332) | 52.11% |
| css-forms | 13.30% | (2/15) | 13.33% | (2/15) | 13.33% |
| css-gaps | 6.80% | (26/381) | 6.82% | (26/381) | 6.82% |
| css-grid | 37.40% | (684/1950) | 35.08% | (2080/5145) | 40.43% |
| css-highlight-api | 13.20% | (13/98) | 13.27% | (13/98) | 13.27% |
| css-image-animation | 68.10% | (15/22) | 68.18% | (15/22) | 68.18% |
| css-images | 26.90% | (126/468) | 26.92% | (126/468) | 26.92% |
| css-inline | 14.20% | (26/186) | 13.98% | (31/385) | 8.05% |
| css-layout-api | 0.00% | (0/135) | 0.00% | (0/135) | 0.00% |
| css-lists | 33.70% | (59/175) | 33.71% | (59/175) | 33.71% |
| css-logical | 33.30% | (2/6) | 33.33% | (2/6) | 33.33% |
| css-masking | 42.60% | (160/375) | 42.67% | (160/375) | 42.67% |
| css-motion-path | 100.00% | (1/1) | 100.00% | (1/1) | 100.00% |
| css-multicol | 28.70% | (164/572) | 28.67% | (166/588) | 28.23% |
| css-nesting | 52.30% | (11/21) | 52.38% | (11/21) | 52.38% |
| css-overflow | 26.90% | (150/560) | 26.79% | (174/631) | 27.58% |
| css-page | 38.10% | (85/223) | 38.12% | (85/223) | 38.12% |
| css-paint-api | 93.00% | (107/115) | 93.04% | (107/115) | 93.04% |
| css-position | 20.00% | (50/253) | 19.76% | (60/295) | 20.34% |
| css-properties-values-api | 55.50% | (5/9) | 55.56% | (5/9) | 55.56% |
| css-pseudo | 34.20% | (86/251) | 34.26% | (86/251) | 34.26% |
| css-rhythm | 19.60% | (3/20) | 15.00% | (16/46) | 34.78% |
| css-ruby | 33.10% | (51/154) | 33.12% | (51/154) | 33.12% |
| css-scroll-anchoring | 50.00% | (2/4) | 50.00% | (2/4) | 50.00% |
| css-scroll-snap | 14.80% | (4/27) | 14.81% | (4/27) | 14.81% |
| css-scrollbars | 100.00% | (31/31) | 100.00% | (31/31) | 100.00% |
| css-shadow | 7.10% | (8/112) | 7.14% | (8/112) | 7.14% |
| css-shapes | 13.10% | (31/235) | 13.19% | (31/235) | 13.19% |
| css-sizing | 41.00% | (248/637) | 38.93% | (628/1624) | 38.67% |
| css-style-attr | 93.70% | (15/16) | 93.75% | (15/16) | 93.75% |
| css-syntax | 20.00% | (1/5) | 20.00% | (1/5) | 20.00% |
| css-tables | 37.30% | (78/225) | 34.67% | (169/570) | 29.65% |
| css-text | 45.90% | (653/1422) | 45.92% | (783/1613) | 48.54% |
| css-text-decor | 26.60% | (77/289) | 26.64% | (77/289) | 26.64% |
| css-transforms | 51.70% | (414/800) | 51.75% | (414/800) | 51.75% |
| css-transitions | 50.00% | (4/8) | 50.00% | (4/8) | 50.00% |
| css-typed-om | 0.00% | (0/5) | 0.00% | (0/5) | 0.00% |
| css-ui | 90.50% | (899/993) | 90.53% | (899/993) | 90.53% |
| css-values | 55.70% | (131/235) | 55.74% | (131/235) | 55.74% |
| css-variables | 98.30% | (181/184) | 98.37% | (186/189) | 98.41% |
| css-view-transitions | 29.50% | (91/308) | 29.55% | (91/308) | 29.55% |
| css-viewport | 74.00% | (74/100) | 74.00% | (74/100) | 74.00% |
| css-will-change | 45.80% | (22/48) | 45.83% | (22/48) | 45.83% |
| css-writing-modes | 13.60% | (149/1089) | 13.68% | (149/1089) | 13.68% |
| css-zoom | 100.00% | (1/1) | 100.00% | (1/1) | 100.00% |
| cssom | 8.30% | (1/12) | 8.33% | (1/12) | 8.33% |
| cssom-view | 45.40% | (5/11) | 45.45% | (5/11) | 45.45% |
| fill-stroke | 0.00% | (0/1) | 0.00% | (0/1) | 0.00% |
| filter-effects | 45.40% | (151/332) | 45.48% | (151/332) | 45.48% |
| mediaqueries | 74.50% | (44/59) | 74.58% | (44/59) | 74.58% |
| motion | 6.00% | (6/100) | 6.00% | (6/100) | 6.00% |
| printing | 75.00% | (12/16) | 75.00% | (12/16) | 75.00% |
| selectors | 21.10% | (49/232) | 21.12% | (49/232) | 21.12% |