== Background
Many of our banners are not accessible by default in night mode
https://ko.m.wikipedia.org/wiki/?minervanightmode=1&banner=wikilovesfolklore2024_banner
For example seen on Korean:
{F42649860}
== User story
* As a reader viewing night mode, I don't want unreadable banners to degrade my experience.
* As someone running a banner campaign I'd like to choose whether my banner can be adapted for night theme.
== Requirements
[] By default banners should be accessible.
[] Users making banners should know that they need to test on night mode and be able to test on night mode.
== Discussion points
We will talk to someone from Fundraising Tech about the following:
[] Should banners default to light theme
[] Do we want to support night themed banners in future
[] What is the correct short term and long term solution for banners in night theme.
Possible solutions:
* The rule `.banner-container` should define the content as black (#333).
* CentralNotice could add rule by default.
* Banners themselves should be updated (preferred -as it's most feature proof - and we may want to run banners that work in both night and light themes in future)