Pricing component with toggle

As you can see I can't complete imitate the original challenge due to my limited knowledge in CSS field. I tried to set padding and change height of middle container to be bigger than both left and right containers, it didn't work though. Instead of expanding vertically like the original design, it keep compressing the inner content instead. Learning more about grid should help fix this problem but I just can't wrap around it for the time being. Any feedback would be highly appreciated.