ChartJS and Flexbox not so responsive

Has anyone experience using flexbox and chartjs? I have made a grid system using flex and now I insert some charts. My problem is that when I minimize the width of the screen, there's only 1 column that is visible. That works fine. But when I expand the screen size again, that column seems just to expand the whole width, probably because of chartjs. I might need to add some to my flex system?