vis.js timeline element set content same size as outer element

in vis.js timeline you can set the own elements to overflow the item box like in this example.
Is there also an way that my custom element is exactly the same size as the VISIBLE item box on the screen?
By default it is the same size which is good until the item leaves the visible page on the left/right. After that a translateX() gets added to the own content which moves my progressbar out of the container.
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What I want:

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Is there a way to achieve this without doing hacky things? I calculate the negative translate(X) on every event and with an interval right now which is just bad.

Thank you very much 🙂