Twenty Twenty-One: Duotone on images not applied in dark mode

[walbo]

Twentytwenty one adds a filter to reduced the brightness and contrast on images to make them easier on the eyes. See ​https://github.com/WordPress/twentytwentyone-dark-mode/issues/17

The issue is that this filter overwrites the filter used to add duotone.

Steps to recreate:

1. Create a page and add a image with duotone.
2. Visit the page frontend with dark mode enabled. Toggle to lightmode and the duodone shows.

Trac ticket: https://core.trac.wordpress.org/ticket/53531#ticket

[desrosj]

Thanks @walbo! This one looks good to me in my testing.

[desrosj]

In 51253:

Twenty Twenty-One: Ensure Duotone images are displayed correctly in Dark Mode.

This reduces the specificity of the CSS selector applying a dimming effect to images so that the new Duotone feature is properly applied to images.

Props walbo.
Fixes #53531.