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Dataset 20261011-0550-f160c57 · measured 2026-10-11 05:50 UTC
mask-composite
◐matches Chrome on some values1 of 4 examples match Chromecss-masking-1
Some of the examples match Chrome and some do not. The count beside the verdict says how many — 11 of 12 — and the values that differ are listed on the property page. It is neither a pass nor a failure, and filing it under either would be a lie in one direction.
Here: 1 of 4 examples match Chrome. The 3 that do not: mask-composite:subtract, mask-composite:exclude, mask-composite:subtract — shown first below, each with its difference map.
What the specification says
- Initial value
- add
- Applies to
- All elements. In SVG, it applies to container elements without the defs element and all graphics elements
- Inherited
- no
- Percentages
- n/a
- Computed value
- list, each item the keyword as specified
- Syntax
- <compositing-operator>#
The measurements
4 examples, 1 of them matching Chrome, the rest first. Each is one declaration on a small page, drawn by Chrome and by our engine. Drag the handle to wipe between them.
mask-composite:subtract✕renders differently
Our renderChrome10,976 pixels differ from Chrome, the largest by 27 of 255 on one channel.
- Differing pixels
- 10,976
- Max channel delta
- 27
mask-composite:exclude✕renders differently
Our renderChrome13,879 pixels differ from Chrome, the largest by 27 of 255 on one channel.
- Differing pixels
- 13,879
- Max channel delta
- 27
mask-composite:subtract✕renders differently
Our renderChrome28 pixels differ from Chrome, the largest by 101 of 255 on one channel.
- Differing pixels
- 28
- Max channel delta
- 101
mask-composite:intersect≈below the visible threshold
Our renderChrome14,755 pixels differ from Chrome, the largest by 3 of 255 on one channel.
- Differing pixels
- 14,755
- Max channel delta
- 3
Which values were measured
“Supported” on one example means “supported at the value we tried”. The property’s declared grammar has 4 branches; 3 of them carry a measurement. The publishing ceiling is 12 examples per property — a branch past it is left out by our choice, not by accident.
| Value | Measured |
|---|---|
| subtract | ✕renders differently |
| intersect | ≈below the visible threshold |
| exclude | ✕renders differently |
| add | not measured |
Measured against Chrome 148.0.7778.96 on 2026-10-11, with up to 40 candidate values tried per property. All properties · How the measurement works