Use Light Icons When Using Dark Theme

Is your feature request related to a problem? Please describe.
The icons are black by default. Using Dark theme will change most of the icons to white ones, but it doesn't apply on the icons in ServerInfo.

Describe the solution you'd like
Apply light icons on Dark theme. It requires CSS abilities which I am currently unable to implement.

Server configuration

Nextcloud version: 21.0.1

[joshtrichards]

Fixed by #396