This feature is not Baseline because it does not work in some of the most widely-used browsers.
The fallback read-only property of the CSSVariableReferenceValue interface returns the custom property fallback value of the CSSVariableReferenceValue.
| Desktop | Mobile | |||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chrome | Edge | Firefox | Opera | Safari | Chrome Android | Firefox for Android | Opera Android | Safari on IOS | Samsung Internet | WebView Android | WebView on iOS | |
fallback |
66 | 79 | No | 53 | 16.4 | 66 | No | 47 | 16.4 | 9.0 | 66 | 16.4 |
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https://developer.mozilla.org/en-US/docs/Web/API/CSSVariableReferenceValue/fallback