backdrop-filter Behind-Element Blur
Separate backdrop sampling from element filter, no browser support/stacking/backdrop-root resolution implied. Explicit supplied computed/layout context only; not a browser cascade/layout engine or cross-browser guarantee.
Description
Backdrop-filter samples content behind an element while filter acts on its rendered group.
Backdrop-filter samples content behind an element while filter acts on its rendered group.1
Visibility of a filtered backdrop also depends on the element's coverage. Use backdrop-filter Behind-Element Blur to look up a supported term.
When to use backdrop-filter Behind-Element Blur
Use backdrop-filter Behind-Element Blur to look up a supported term. Choose the exact supported token from the table; preserve its punctuation and capitalization.
How to use backdrop-filter Behind-Element Blur and understand its results
- Choose the exact supported token from the table; preserve its punctuation and capitalization.
- Enter Filter kind using the field table and validation rules below, then run the tool.
- Read Meaning and interpret units, signs, ordering and placeholders as explained below.
- If the tool reports an input error, correct that field and rerun. A successful false result, empty match list or unknown-evidence placeholder has the specific meaning described here; check the limitations before applying the result.
| Input field | Meaning | Value type | Requirement |
|---|---|---|---|
| filterKind | Filter kind | string | Required; constraints below |
Enter one of the exact supported filterKind tokens in the table below. The implementation performs a case-sensitive lookup and returns the stored meaning without interpreting a stylesheet, audio recording or performance. Unsupported tokens, added whitespace and alternate capitalization are input errors. The entries describe a bounded vocabulary rather than every valid value in the wider topic.
meaning = storedTable[exactSupportedToken] Field order, units and branch conditions follow the implementation explanation above.
| Exact supported token | Stored meaning |
|---|---|
| backdrop-filter | filters sampled backdrop behind element; transparent coverage can reveal result |
| filter | filters element rendered group including descendants |
| Output field | Meaning | Value type |
|---|---|---|
| meaning | Stored explanation for the exact supported token. | string |
{
"input": {
"filterKind": "backdrop-filter"
},
"output": {
"meaning": "filters sampled backdrop behind element; transparent coverage can reveal result"
}
}Limitations and assumptions
Visibility of a filtered backdrop also depends on the element's coverage. Apply the exact scope and assumptions described above.
All listed fields require explicit values. Unexpected fields, incorrect types, nonfinite numbers and sparse arrays fail validation. Domain-specific bounds, alignments and supported tokens are stated above; extremely large inputs or outputs can also be rejected. These errors differ from successful results such as false, no matches or unknown evidence.
Alternative or Complementary methods
Use filter drop-shadow vs box-shadow Diff for a related task: Box shadows use a box silhouette while filter drop shadows use rendered alpha.
Use mask-image Alpha vs Luminance Mode Lookup for a related task: Mask coverage can depend on alpha alone or on luminance multiplied by alpha.
References
-
backdrop-filter Behind-Element Blur — tool.io
Similar or alternative tools
- filter drop-shadow vs box-shadow Diff
Box shadows use a box silhouette while filter drop shadows use rendered alpha.
- mask-image Alpha vs Luminance Mode Lookup
Mask coverage can depend on alpha alone or on luminance multiplied by alpha.