Caption overlay not flush for medium images

Hi Tom,

I've got an issue with the captions not aligning to the base of medium-size images. They display fine with full-size images.

I can fix it with this:

.wp-caption .wp-caption-text {
bottom: 20px;
}

But of course, it then breaks the captions for full-size images.

Here's where it's happening: cefnmawr-pri.wrexham.sch.uk/healthy-week/

Can you help with a workaround?

Thanks,

Chris