Panel docs website strangeness

The bokeh plot on this page initially loaded with a light theme, but after pressing shift-refresh, some of the time the plot then loads with a dark theme. This occurred in both Chrome and Microsoft Edge.

My system and browsers are configured to use dark themes, so I guess it is possible there is some sort of magical automatic theme detection happening.

Here is a screenshot of the plot when it rendered with a light theme:

And here is a screenshot of the plot when it rendered with a dark theme:

I would guess this might be a bokeh issue of some kind.

This seems somewhat superficial, but I wonder if there is a bug that should be reported somewhere. I also wonder if there is some sort of automagic theme detection going on here, and if so, if that can be applied to panel and/or bokeh objects more generally, particularly for jupyterlab notebooks in my case.

Hi @brl0

My thoughts are

  1. I have something experienced getting a dark theme when I move from one page that has been using a dark theme to another page which is not using a dark theme. For example when navigating

  2. I don’t think it has anything to do with the browser theme being dark as the theme/ style of a bokeh plot would not be something it knows about (I belive).

  3. I can reproduce the problem. The page also loads with a “dark theme” for me when I navigate there the first time.

Problem reproduced by navigating to page

Problem solved by hard refresh

Problem recreated by refreshing the page

  1. I think this is worthy of being reported as a bug on [github](( Would you do that @brl0? Thanks.

The behaviour is indeed strange. In the video below I update the page and you can see it’s normally dark themed but at 00:24 I get a light themed version back.

Futher investigation shows that the app above is an embedded iframe from Panel Application (

That link shows the same behaviour. And it’s both the layout and the theme that can change.

My guess it the problem is that it is a part of a larger site where some of the pages are dark themed and that dark theme is applied across users and session (clearly a bug).

I have reported this as a bug Distribution Tabs Demo affected by other pages in panel-gallery · Issue #2167 · holoviz/panel (

Thanks @Marc for taking a look at this and reporting!

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