White backgrounds appearing unexpectedly with Horizon theme

Product Support

AI-generated summary

donaldsoncd reports that specific areas of their Discourse forum, including the composer and main interface, have unexpectedly turned white instead of the usual cream background when using the Horizon theme in light mode. This issue affects their admin account but not test user accounts. Initial troubleshooting ruled out the new composer redesign. Using developer tools, the user discovered that the CSS variable --d-content-background was calculating as nearly white rather than the intended palette color (#FFFDF1). Manually overriding this variable resolved the visual glitch, but the user seeks a permanent fix, unsure if it stems from the theme, a core update, or configuration.

chapoi suggests narrowing down the cause by testing in Safe Mode and switching to the Foundation theme to see if the issue persists. They also recommend checking if any staff-only enabled features or upcoming changes might be contributing to the conflict.

1

Hello!

Today, I noticed that some areas of my Discourse forum have suddenly started appearing white instead of my usual cream background. This includes the composer and parts of the main interface.

Examples from my main admin account:

SCR-20261112-jbte
SCR-20261112-jbte1526×792 44.4 KB

image
image3022×1078 247 KB

Here is the issue not occurring with test user account:

SCR-20261112-jbrr
SCR-20261112-jbrr1514×792 40.3 KB

SCR-20261112-jygl
SCR-20261112-jygl3016×1022 228 KB

I’m using the Horizon theme with a custom color palette and using light mode with both accounts. Here’s screenshots:

SCR-20261112-jstk
SCR-20261112-jstk1920×1091 177 KB

SCR-20261112-jsqa
SCR-20261112-jsqa3024×1670 340 KB

SCR-20261112-jsgd
SCR-20261112-jsgd1992×1070 152 KB

I initially thought the issue was related to the new composer redesign, but disabling that didn’t resolve it.

I’m not a developer, so I’m unsure whether this is a bug in Horizon, a recent Discourse change, or something specific to my configuration.

With some AI help, I used Chrome’s developer tools to investigate. It looks like the CSS variable --d-content-background is being calculated as nearly white, even though my palette’s background color is #FFFDF1. Temporarily changing that variable to #FFFDF1 fixed the appearance.

Has anyone else encountered this and can you help me resolve?

2

It’s helpful to try in safe mode, to see if it persists, and also try on Foundation please. It helps to narrow things down.

Also have a look if you have any upcoming changes only enabled for staff maybe, could be a culprit too.