User Agent: Mozilla/5.0 (X11; Linux x86_64; rv:88.0) Gecko/20100101 Firefox/88.0

Steps to reproduce:

The CSS property filter on the html tag doesn't work as expected.

To reproduce, set a filter on the HTML tag using CSS. ex:filter: blur(10px);

The attached file is a simple HTML page to reproduce the bug.

Actual results:

First of all, it disable fixed position on the page. They become absolute instead of fixed.

Then, if the filter is invert(1), the filter is applied on the page but on the HTML background. So a black background on the HTML tag doesn't became white.

Expected results:

Fixed positioned element shouldn't be modified by the filter. And the invert filter should apply to html background.

The Bugbug bot thinks this bug should belong to the 'Core::Layout' component, and is moving the bug to that component. Please revert this change in case you think the bot is wrong.

This was a spec change see bug 1423746.