Chat with Fluid Layout

I am familiar with a stock example:

The example shows how to make a chart responsive to the size changes. In order to make it work, I need to specify a percentage of a parent container. But I dont want to have my chart any smaller than the available space. I want it to always take the maximum of it. Any suggestions?

Thanks

Something like https://codepen.io/etpinard/pen/EQvxJz?editors=0010 should do the trick.