Theme change not applied to README.md preview

[Lomaiin]

Describe the bug

Hey, I found a minor bug in the UI when changing themes from a page with README.md/PREADME.md.
The new theme will be applied everywhere except in the README preview.
Simply reloading the page will fix the problem.

It's really a minor bug. I don't really expect it to be fixed, but I wanted you to be aware of it :)

To Reproduce

To see it, go to a page with README.md, then change the theme.

Expected behavior

Apply the theme to the preview.

Screenshots

Server details (if you're NOT using docker/podman)

• run copyparty with --version and grab the last 3 lines (they start with copyparty, CPython, sqlite) and paste them below this line:
  copyparty v1.19.23 "usernames" (2025-12-17)
  CPython v3.13.9 on Linux64 [GCC 14.3.0]
  sqlite 3.50.4*1 | jinja 3.1.6 | pyftpd 2.0.1 | tftp (None)

[isaacjstriker]

I was digging around a little, according to dev tools, it looks like the iframe that holds the README.md doesn't update correctly until the page is re-rendered on page refresh.

So, when I change themes using the drop down, the "html class" in the <iframe> tag looks like this:

class="iframe dz d z read write

Then, without changing anything else, when the page is refreshed it changes to:

class="iframe cy c y read write

Maybe the iframe isn't getting updated correctly? I'm not sure how the logic works with the dropdown changing the theme, but this might be a good place to start for someone who knows more than me haha. I'll keep digging, though.

[9001]

ah, I can provide some context --

the readme is running inside a sandbox, and the sandbox does not have privileges to reach out to the webserver to fetch the css and javascript necessary to render correctly, so it is fed into the sandboxed iframe along with the contents to render.

There's a javascript function which generates the correct html based on the currently active css/js in the parent website; that's function sandbox -- the way to fix thiis would be to rerun this and regenerate the html + fully reload the iframe when the theme is changed, but I haven't yet looked into how feasible this is -- the limitation is the intentional sandboxing making realtime updates difficult