Mask in episode 4 has no shadow

[K-Meech]

What is the problem?

The mask in episode 4 is shown with no shadow around it, even though it is specified with .image-with-shadow in the markdown

This makes it difficult to interpret as the white parts of the image blend directly into the lesson background:

Location of problem (optional)

No response

[tobyhodges]

No equivalent to the image-with-shadow class has yet been implemented in varnish, the package that defines layout and styling in the new lesson infrastructure. I have been meaning to finish up a PR to address this, which I started but it turned out to be more complicated than I predicted.