darkroom filmstrip color label dot does not scale with dpi

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

on a hidpi screen, one can override the dpi and get most elements to scale. however, the color label dot does not seem to scale, making it really hard to see which ones are applied to any picture.

furthermore, it would seem that it's not possible to change the size of these color label dots from css

Steps to reproduce

1. open darktable on a hidpi screen
2. go to darkroom
3. apply a color label (e.g. F4 for blue while hovering over a pic in the filmstrip at bottom)
4. dot is barely visible, especially if you hover away from the pic
5. go to settings and override dpi to scale UI
6. see how all elements are now bigger
7. see how the color label dot has not changed in size

Expected behavior

ideally, the dot should scale with the dpi setting from system or from DT settings. or, a workaround would be the ability to overide the px size of the color label dot in css

Logfile | Screenshot | Screencast

No response

Commit

No response

Where did you obtain darktable from?

OBS build

darktable version

5.2.1

What OS are you using?

Linux

What is the version of your OS?

ubuntu 25.04

Describe your system

No response

Are you using OpenCL GPU in darktable?

Yes

If yes, what is the GPU card and driver?

this happens on both my desktop (Radeon RX 6800 XT) and laptop (nvidia gpu)

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response

Start by reproducing the issue in darkroom on a HiDPI Linux display, then inspect the filmstrip color-label dot implementation and its styling or DPI-scaling path. The change is done when the dot scales with the system or overridden DPI, or its size can be overridden through CSS, and the result is verified for hovered and non-hovered images.