The images overflowing off the edge happens on the public version of the card, if you’re logged in the UI makes the images shrink to the card width.
Hi James!
Marie with Guru Support here. I saw your product feedback and wanted to see if you’ve tried shrinking your uploaded images by clicking and dragging the dark grey bar located on the right-hand side of the image? This might help with the control over sizing you’re looking to have within the Card editor.
Regarding your comment about the images overflowing in the public version of the Card, this is actually a known bug.
Our Engineering team is actively working on the fix. I’ve set a reminder to reach back out to you and will let you know when it is resolved.
Hope this information is helpful! 
Yes, dragging the bar to resize the images does work, even just a few pixels. Thanks :)
Oh awesome, @James Andrewartha, I’m glad to hear it works! Our engineering team also just released the fix that will stop images from overflowing in the public version of the Card.
Thanks again for mentioning this and I’m glad we could connect. 
Updated idea statusOpen→Complete