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fix issue: Backdrop Root concept undocumented #40627

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fix issue: Backdrop Root concept undocumented #40627

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65bb447
fix issue on backdrop-filter
kb42 Aug 4, 2025
fee12df
Merge branch 'main' into cssBackdrop
kb42 Aug 4, 2025
ef022ee
Merge branch 'main' into cssBackdrop
kb42 Aug 7, 2025
7b5ee9e
Merge branch 'main' into cssBackdrop
kb42 Aug 9, 2025
67b4beb
Merge branch 'main' into cssBackdrop
kb42 Aug 9, 2025
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14 changes: 13 additions & 1 deletion files/en-us/web/css/backdrop-filter/index.md
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Expand Up @@ -6,7 +6,19 @@ browser-compat: css.properties.backdrop-filter
sidebar: cssref
---

The **`backdrop-filter`** [CSS](/en-US/docs/Web/CSS) property lets you apply graphical effects such as blurring or color shifting to the area behind an element. Because it applies to everything _behind_ the element, to see the effect the element or its background needs to be transparent or partially transparent.
The **`backdrop-filter`** CSS property lets you apply graphical effects such as blurring or color shifting to an element's **backdrop image**, which are the pixels painted behind the element up to its nearest ancestor Backdrop Root. To see the effect, the element (or its background) must be transparent or partially transparent.

> [!NOTE]
> Filters do not apply to pixels behind the element that originate from outside its nearest ancestor Backdrop Root.
> A Backdrop Root is the nearest ancestor that is one of:
>
> - the root `<html>` element
> - an element with a `filter` property other than `none`
> - an element with `opacity` less than 1
> - an element with `mask`, `mask-image`, `mask-border`, or `clip-path` other than `none`
> - an element with `backdrop-filter` other than `none`
> - an element with `mix-blend-mode` other than `normal`
> - an element with `will-change` specifying any of the above properties

{{InteractiveExample("CSS Demo: backdrop-filter()")}}

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