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Status

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

CSS PropertiesHTML ElementsEventsWPT Tests

CSS Properties are grouped into logical feature grouping, and within each group they are roughly ordered by the percentage of web pages that use that property. You can generally assume that if the longhand versions of a property are supported then the shorthand version will also be supported and vice-versa.

Core

% usePropertyStatus
93%display
display:inline✅ Supported
display:block✅ Supported
display:inline-block✅ Supported
display:flex✅ Supported
display:grid✅ Supported

Subgrid is not supported

display:table⚠️ Partial support taffy#467

Table layout is emulated with CSS Grid.

display:grid-lanes❌ Not supported taffy#910
display:none✅ Supported
display:contents✅ Supported
92%position
position:static❌ Not supported
position:relative✅ Supported
position:absolute✅ Supported
position:fixed❌ Not supported
position:sticky❌ Not supported

Note that because 'position:static' is not supported, 'position:absolute' nodes are always positioned relative to their immediate parent

87%overflow
overflow:visible✅ Supported
overflow:clip✅ Supported
overflow:hidden✅ Supported
overflow:scroll✅ Supported
overflow:auto❌ Not supported
85%box-sizing✅ Supported
86%z-index✅ Supported
85%cursor
keyword✅ Supported
custom image❌ Not supported
81%content (::before / ::after)
string✅ Supported
image❌ Not supported
gradient❌ Not supported
counter❌ Not supported
74%float✅ Supported
61%clear✅ Supported
41%order✅ Supported
30%zoom❌ Not supported

Visibility & Isolation

% usePropertyStatus
87%opacity✅ Supported

Nodes with opacity are currently clipped regardless of the overflow style

80%visibility✅ Supported
21%contain❌ Not supported
18%isolation❌ Not supported
9%content-visibility❌ Not supported

Clipping & Masking

% usePropertyStatus
53%clip-path✅ Supported
26%mask-image✅ Supported
13%mask-position✅ Supported
12%mask-repeat✅ Supported
12%mask-size✅ Supported
11%mask-composite✅ Supported
3%mask-mode❌ Not supported
1%mask-origin❌ Not supported
1%mask-clip❌ Not supported

Sizing & Positioning

Flow relative versions of properties (e.g. max-inline-size) are also supported

% usePropertyStatus
93%width / height✅ Supported
81%min-width / min-height✅ Supported
83%max-width / max-height✅ Supported
90%inset✅ Supported
62%gap✅ Supported
35%aspect-ratio✅ Supported
52%object-fit✅ Supported
20%object-position✅ Supported

Padding, Margin & Borders

Flow relative versions of properties (e.g. padding-inline-start) are also supported

% usePropertyStatus
91%padding✅ Supported
91%margin✅ Supported
86%border-radius✅ Supported
77%border-color✅ Supported
66%border-width✅ Supported
62%border-style❌ Not supported
6%border-image❌ Not supported

Text Direction

% usePropertyStatus
46%direction⚠️ Partial support

Supported for block-level but not inline-level boxes. Auto-detection of RTL text is support for inline content.

14%all✅ Supported
14%unicode-bidi❌ Not supported
8%writing-mode❌ Not supported

Font

% usePropertyStatus
72%@font-face✅ Supported

It is not yet possible to override the family name or other matching criteria.

90%font-size✅ Supported
88%font-family✅ Supported
88%font-weight✅ Supported
79%font-style✅ Supported
52%font-display❌ Not supported
29%font-variant❌ Not supported
28%font-stretch✅ Supported
30%font-feature-settings❌ Not supported blitz#184
21%font-variation-settings✅ Supported
7%font-variant-ligatures❌ Not supported

Text

% usePropertyStatus
90%color✅ Supported
88%text-align✅ Supported
86%line-height✅ Supported
83%text-decoration✅ Supported
82%vertical-align❌ Not supported parley#291
81%white-space-collapse⚠️ Partial support
81%text-wrap-mode✅ Supported
72%text-transform
uppercase✅ Supported
lowercase✅ Supported
capitalize❌ Not supported
67%letter-spacing✅ Supported
65%text-overflow❌ Not supported parley#304
56%word-break✅ Supported
43%webkit-line-clamp❌ Not supported
41%overflow-wrap / word-wrap✅ Supported
37%text-indent✅ Supported
22%text-wrap-style❌ Not supported
22%text-decoration-line❌ Not supported
17%text-underline-offset❌ Not supported
16%text-decoration-color✅ Supported
13%word-spacing✅ Supported
14%tab-size❌ Not supported
12%text-decoration-thickness❌ Not supported
11%hyphens❌ Not supported
12%webkit-text-fill-color❌ Not supported
9%quotes❌ Not supported

Backgrounds

% usePropertyStatus
90%background-color✅ Supported
79%background-image✅ Supported
75%background-position✅ Supported
72%background-size✅ Supported
72%background-repeat✅ Supported
70%background-clip✅ Supported
9%background-origin✅ Supported
9%background-attachment❌ Not supported

Flexbox

% usePropertyStatus
74%flex-direction✅ Supported
69%flex-wrap✅ Supported
58%flex-grow✅ Supported
61%flex-shrink✅ Supported
42%flex-basis✅ Supported
0%webkit-box-*❌ Not supported

These properties are for the legacy flexbox model that was never widely adopted. Blitz does not ever intend to support these.

Grid

% usePropertyStatus
46%grid-template-{rows,columns}
px / percentage / fr✅ Supported
min-content / max-content / auto✅ Supported
fit-content()✅ Supported
named lines✅ Supported
subgrid❌ Not supported taffy#468
25%grid-{row,column}✅ Supported
23%grid-area✅ Supported
18%grid-template-areas✅ Supported
14%grid-auto-flow✅ Supported
12%grid-auto-{rows,columns}✅ Supported

Box Alignment

% usePropertyStatus
79%{align,justify}-content✅ Supported
79%{align,justify}-items✅ Supported
52%{align,justify}-self✅ Supported

2D Transforms

% usePropertyStatus
84%transform✅ Supported
57%transform-origin✅ Supported
15%scale✅ Supported
10%rotate✅ Supported
10%translate✅ Supported
5%transform-box❌ Not supported

3D Transforms

3D transforms are not currently supported

% usePropertyStatus
84%transform❌ Not supported
57%transform-origin❌ Not supported
15%scale❌ Not supported
10%rotate❌ Not supported
10%translate❌ Not supported
21%backface-visibility❌ Not supported
13%transform-style❌ Not supported
10%perspective❌ Not supported
5%transform-box❌ Not supported

Transitions & Animations

% usePropertyStatus
80%Transitions✅ Supported
69%Animations✅ Supported

Composition & Effects

% usePropertyStatus
82%box-shadow✅ Supported
51%filter⚠️ Partial support

Supported with the Skia backend. Partially supported (blur and drop-shadow only) with Vello Hybrid.

46%outline✅ Supported
44%text-shadow❌ Not supported
32%backdrop-filter⚠️ Partial support

Supported with the Skia backend.

13%mix-blend-mode❌ Not supported
4%background-blend-mode❌ Not supported

Lists

% usePropertyStatus
48%list-style-type✅ Supported
12%list-style-position✅ Supported
11%counter-increment❌ Not supported
9%counter-reset❌ Not supported

Tables

% usePropertyStatus
50%border-collapse⚠️ Partial support

It is currently assumed that borders in tables with collapsed borders are uniform (have the same width/style/color). The border styles from the first cell are used.

32%border-spacing✅ Supported
21%table-layout✅ Supported
7%caption-side❌ Not supported

SVG

Rendering SVGs (including inline SVGs) is supported, but styling SVGs is not yet supported.

% usePropertyStatus
64%fill❌ Not supported
41%stroke❌ Not supported
43%stroke-width❌ Not supported
29%stroke-dashoffset❌ Not supported
28%stroke-dasharray❌ Not supported
14%fill-opacity❌ Not supported
14%stroke-linecap❌ Not supported
9%stroke-miterlimit❌ Not supported
7%stroke-opacity❌ Not supported

Interaction & Pointer events

% usePropertyStatus
71%pointer-events✅ Supported
67%user-select
auto✅ Supported

Pseudo-elements are currently selectable by default

text✅ Supported
none⚠️ Partial support

Current implementation only prevents selections from being started in elements with user-select:none

all❌ Not supported
44%touch-action❌ Not supported
15%caret-color✅ Supported
8%webkit-user-drag❌ Not supported
0%webkit-tap-highlight-color❌ Not supported

User Agent Hints

% usePropertyStatus
62%webkit-font-smoothing❌ Not supported
49%appearance❌ Not supported
39%will-change❌ Not supported
34%text-rendering❌ Not supported
21%text-size-adjust❌ Not supported
22%color-scheme❌ Not supported
19%forced-color-adjust❌ Not supported
18%scrollbar-color❌ Not supported
9%overflow-anchor❌ Not supported
7%image-rendering❌ Not supported

Miscellaneous / Other

% usePropertyStatus
40%scrollbar-width❌ Not supported
37%resize❌ Not supported
11%speak❌ Not supported
8%container❌ Not supported

Scroll Behaviour

% usePropertyStatus
20%scroll-behavior❌ Not supported
16%scroll-snap-type❌ Not supported
13%scroll-snap-align❌ Not supported
6%scroll-padding❌ Not supported
0%scroll-boundary-behavior❌ Not supported
0%scroll-boundary-behavior-y❌ Not supported

Multi-column Layout

% usePropertyStatus
6%column-count❌ Not supported
3%column-width❌ Not supported
1%column-span❌ Not supported

Anchor Positioning

% usePropertyStatus
0%anchor-scope❌ Not supported
1%anchor-name❌ Not supported
1%position-anchor❌ Not supported
0%position-area❌ Not supported
1%position-try❌ Not supported
0%position-visibility❌ Not supported

@page

% usePropertyStatus
7%size❌ Not supported
3%break-inside❌ Not supported
1%break-after❌ Not supported
1%break-before❌ Not supported