Differences between editor, preview and live


I’ve got an element in my site which I use a repeater with Custom Elements in. Chart.js to be exact.

Every version of the site differs. Scales are in absolutes (so no percentages) so confused why this randomly is different. Is there any ideas why? I’ve included screenshots to show how wildy different they are.

First image is the editor (please ignore the message running through the items, this is hidden), then the preview site and lastly is the published site.