for the slide selection images: these aren't keyboard-operable at the moment because they're images. ideally we'd change these to button elements with images in them, but this may break a lot of CSS. an alternative would be making the images focusable and giving them a button role as well as adding labels to indicate what the "buttons" do
for images in slides, change alt attributes to empty strings. current alt text is redundant with the nearby slide titles.
The carousel is working. We would like to investigate accessibility of it.