Match height of elements to other elements with javascript/css/html?

I did the mosaic with 3 columns. I was not into the columns scrolling separately. Then @williamtisdale gave me a good tip on how to unify the scrolling elements.

But, my groups are all displaying at slightly different heights, so when I try to scroll things get ugly.

I tried to resolve it with conditionals and make the elements respond to each other, but that doesn’t work. And workflows don’t let me adjust the size of the elements.

I am not at all experienced with code beyond simple html stuff for blogs in 2004. I tried figuring out a javascript solution, but I can’t make sense of any of it. Tried searching the forums but nothing seemed to be there.

Any suggestions are appreciated.