Fixed size of chart when resizing

Hi,

I would like to ask you how to achieve that chart doesnt change height in some resolution.
Here is how it looks like on 800x640:


But when I change height to 800x400 I would like to have some minimal size of chart and add scrollbar:
For the "card" I use min-height and preserve the size of "card" I tried it to use also on graph but without effect.


Thanks,

Krpo