If you've ever had a casino offer in hand and been trying to figure out which sailings actually use which cabin category, you know the dance. A Prime offer covers Interior through Balcony; a Signature offer covers all the way up to Suite. Keeping that in your head while scanning a big sailings table is annoying.
Now when you apply one of your casino offers as a filter, the price cells for cabin types that offer actually covers get a green outline. No more second-guessing whether your Choice offer covers that Balcony cabin -- if it's outlined, it's covered.
It's a small visual change that makes the filter dramatically more useful for actually planning which cabin to book.