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:
678aef9 Rename _opt accessor methods to use try_ prefix (#801) (2026-08-26)
| Area | Interop Score | Tests | Test % | Subtests | Subtest % |
|---|---|---|---|---|---|
| Total | 47.70% | (12305/26038) | 47.26% | (17087/35350) | 48.34% |
| CSS2 | 62.50% | (3906/6250) | 62.50% | (3916/6277) | 62.39% |
| WOFF2 | 98.30% | (293/298) | 98.32% | (293/298) | 98.32% |
| compositing | 14.20% | (9/63) | 14.29% | (9/63) | 14.29% |
| css-align | 33.10% | (34/164) | 20.73% | (414/1704) | 24.30% |
| 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 | 65.30% | (472/722) | 65.37% | (472/722) | 65.37% |
| css-borders | 25.80% | (22/85) | 25.88% | (22/85) | 25.88% |
| css-box | 12.80% | (6/109) | 5.50% | (39/227) | 17.18% |
| css-break | 19.80% | (222/1120) | 19.82% | (226/1125) | 20.09% |
| css-cascade | 65.40% | (36/55) | 65.45% | (51/70) | 72.86% |
| css-color | 90.50% | (278/307) | 90.55% | (278/307) | 90.55% |
| css-color-adjust | 23.80% | (5/21) | 23.81% | (5/21) | 23.81% |
| css-conditional | 73.60% | (137/186) | 73.66% | (137/186) | 73.66% |
| css-contain | 55.90% | (249/449) | 55.46% | (323/578) | 55.88% |
| css-content | 9.30% | (6/64) | 9.38% | (6/64) | 9.38% |
| css-counter-styles | 3.30% | (8/240) | 3.33% | (8/240) | 3.33% |
| css-display | 31.90% | (68/213) | 31.92% | (68/213) | 31.92% |
| 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 | 71.00% | (851/1237) | 68.80% | (2529/3544) | 71.36% |
| css-font-loading | 50.00% | (3/6) | 50.00% | (3/6) | 50.00% |
| css-fonts | 50.50% | (193/382) | 50.52% | (193/382) | 50.52% |
| css-forms | 12.50% | (2/16) | 12.50% | (2/16) | 12.50% |
| css-gaps | 6.80% | (26/381) | 6.82% | (26/381) | 6.82% |
| css-grid | 39.30% | (718/1950) | 36.82% | (2542/5145) | 49.41% |
| css-highlight-api | 13.00% | (13/100) | 13.00% | (13/100) | 13.00% |
| css-image-animation | 68.10% | (15/22) | 68.18% | (15/22) | 68.18% |
| css-images | 29.00% | (135/465) | 29.03% | (135/465) | 29.03% |
| css-inline | 14.20% | (26/186) | 13.98% | (31/385) | 8.05% |
| css-layout-api | 5.90% | (8/135) | 5.93% | (8/135) | 5.93% |
| 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 | 44.00% | (165/375) | 44.00% | (165/375) | 44.00% |
| css-motion-path | 100.00% | (1/1) | 100.00% | (1/1) | 100.00% |
| css-multicol | 28.50% | (163/573) | 28.45% | (165/589) | 28.01% |
| css-nesting | 71.40% | (15/21) | 71.43% | (15/21) | 71.43% |
| css-overflow | 27.10% | (151/561) | 26.92% | (181/632) | 28.64% |
| css-page | 39.00% | (89/228) | 39.04% | (89/228) | 39.04% |
| css-paint-api | 93.00% | (107/115) | 93.04% | (107/115) | 93.04% |
| css-position | 21.50% | (55/256) | 21.48% | (72/298) | 24.16% |
| css-properties-values-api | 55.50% | (5/9) | 55.56% | (5/9) | 55.56% |
| css-pseudo | 33.20% | (89/268) | 33.21% | (89/268) | 33.21% |
| css-rhythm | 19.60% | (3/20) | 15.00% | (16/46) | 34.78% |
| css-ruby | 33.30% | (52/156) | 33.33% | (52/156) | 33.33% |
| 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 | 38.70% | (12/31) | 38.71% | (12/31) | 38.71% |
| css-shadow | 7.00% | (8/113) | 7.08% | (8/113) | 7.08% |
| css-shapes | 13.10% | (31/235) | 13.19% | (31/235) | 13.19% |
| css-sizing | 52.50% | (320/637) | 50.24% | (750/1624) | 46.18% |
| css-style-attr | 93.70% | (15/16) | 93.75% | (15/16) | 93.75% |
| css-syntax | 100.00% | (1/1) | 100.00% | (1/1) | 100.00% |
| css-tables | 41.00% | (87/227) | 38.33% | (178/572) | 31.12% |
| css-text | 47.50% | (718/1513) | 47.46% | (848/1704) | 49.77% |
| css-text-decor | 29.50% | (91/308) | 29.55% | (91/308) | 29.55% |
| css-transforms | 51.50% | (417/809) | 51.55% | (417/809) | 51.55% |
| 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 | 89.50% | (901/1006) | 89.56% | (901/1006) | 89.56% |
| css-values | 55.70% | (131/235) | 55.74% | (131/235) | 55.74% |
| css-variables | 97.80% | (181/185) | 97.84% | (186/190) | 97.89% |
| css-view-transitions | 30.20% | (93/307) | 30.29% | (93/307) | 30.29% |
| css-viewport | 71.50% | (78/109) | 71.56% | (78/109) | 71.56% |
| css-will-change | 45.80% | (22/48) | 45.83% | (22/48) | 45.83% |
| css-writing-modes | 12.60% | (145/1144) | 12.67% | (145/1144) | 12.67% |
| 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 | 36.30% | (4/11) | 36.36% | (4/11) | 36.36% |
| fill-stroke | 0.00% | (0/1) | 0.00% | (0/1) | 0.00% |
| filter-effects | 45.90% | (154/335) | 45.97% | (154/335) | 45.97% |
| mediaqueries | 74.50% | (44/59) | 74.58% | (44/59) | 74.58% |
| motion | 6.00% | (6/100) | 6.00% | (6/100) | 6.00% |
| printing | 72.40% | (21/29) | 72.41% | (21/29) | 72.41% |
| selectors | 20.90% | (50/239) | 20.92% | (50/239) | 20.92% |