Responsiveness - White space on small devices.

[zuhairabs]

On smaller devices there is white space issue as shown in attached image. Is there a way to avoid the whitespace, it is caused by 20rem/15rem width on class .wt-chart-box. Reproduce Issue: Open the below link on mobile device and zoom out. https://dev.webtrees.net/demo-stable/index.php?route=%2Fdemo-stable%2Ftree%2Fdemo%2Ffamily-book-2-5-0%2Fi1