Expenses chart component - built with React, responsive Flex layout

I managed to successfully implement all of the main features, but what's the best solution to have the graph's bars height scale dynamically with the data from the JSON file? I figured a good way to get that working is to use percentages for the bars' height, with the % value being proportional to the biggest data point (determined using Math.max() with JS), which would always take up 100% height. I also added the bar legend hover element as a child of the actual bar <div> so that I could use "position: absolute" and "top: 0" to always have them show up above the bars, but I'm not sure if this is the best approach. Thanks!