Fixes for listings 5.3, 5.10 in Chapter 5.

[yangmillstheory]

Just minor bugs - should be evident in the changeset.

Also, I took the liberty of:

• making sure the "gallery" text for Fuji-X100 doesn't overflow into the adjacent product
• making sure that the product icons appear; previously they weren't

Before:

After:
Without hover:

On hover:

I haven't read through the chapter on testing yet, so I'm wondering if the tests are passing. Could you let me know how to check them?

Thanks for writing the book!

[boundvariable]

Thanks for the PRs. I haven't forgotten about them. Will go through them next week.