How to style a selector's height based on the height of the selector that is being hovered?

Hello friends, first time poster. A friend I know brought a JS solution to a problem that I think can be solved with CSS. But I just can't put my finger on it. The component is the one under "Qualify self-employed borrowers in seconds." at this website: https://baleensolutions.com/ What it does is when you hover one of the three items inside that little scrollbar to the left moves to the correspondent card that is being hovered and changes size to occupy 100% of the height of that element that is being currently hovered. I was thinking of a way to solve the problem with CSS alone but I just can't grasp what would be a feasible way. The element that I am trying to animate is that little scrollbar on the left of those items in the picture.

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