Slider changes when pushed online

Hello everyone! Our experiment includes a slider with originally a triangle marker, which does not seem to work anymore even in builder in the newest PsychoPy version (it is a vertical red line now).

But otherwise, offline the slider works fine - there are lines on the slider indicating where the ticks are, and the labels are in the right places, and the lightbulb lights up as it should.

When I push the slider online, the labels are suddenly on top of one another, there are no more lines indicating ticks, the marker is a broader block, and the lightbulb lights up to only half the brightness. It almost seems like it’s ‘zoomed in’ on, if that makes sense?

I can’t find the issue in the JS-Code, because I am very new at PsychoPy and JS.

I will try and attach images of the slider offline and online. Even if we cannot get the triangle marker back, at least having it look the same as in builder would be a huge help.
Thank you in advance!