"download" icon of a photo viewer is barely visible (shared link, light theme)

[xalt7x]

When you share a folder with pictures unlogged/anonymous user can open them in a viewer. On the right top corner there's three icons - "slides", "download" and "close". With a default light theme "Slides" and "Close" are in a white color but "Download" is black so it's barely visible for a user (screenshot bellow)

It's actually in a CSS

.icon-download {
    background-image: var(--icon-download-000);
}

This color is also used for hidden menu icon of a logged user

But shared links for anonymous user better to use different CSS

.icon-download {
   background-image: var(--icon-download-fff);
}

For now administrator can force some dark theme (e.g. "Breeze Dark") with a "Theming" app.

Steps to reproduce

1. Share link to a folder with pictures
2. Open new tab with that link
3. Open any picture

Expected behaviour

All menu icons has the same color

Actual behaviour

"download" icon is black and barely visible on a dark background

Nextcloud version: 21.0.3 or 22.1.1

[CarlSchwan]

This seems to have already been resolved in master, but I can reproduce in stable22

(screenshot from master)

[szaimen]

dup of nextcloud/viewer#848