Change all or no colours in preview when using dark mode
Currently with dark mode, the background colour of the preview panel (Markdown, don't know if other formats are previewed?) changes to near-black, but the other colours don't change. This makes the preview unreadable since it's black on very dark grey (and e.g. links are dark blue still).
A quick fix presumably would be to explicitly style the preview background to white so that it's unaffected by dark mode, until a full dark colour theme can be implemented.
Arguably the preview should either have the current Builder theme applied, or have a separate fixed (light) theme (since presumably the target, e.g. a GitHub/GitLab README, wouldn't ever be dark.
Also, as an aside, the preview doesn't instantly update when dark mode is toggled - the pane has to be closed then re-opened.